octane and oil thoughts..

[raverjames]

I would be interested in having you state your "facts" as to why Ford specifies 5W-30 oil for the V6 and 5W-20 oil for the GT. So far you have said nothing other than you think my statement is the silliest thing you ever heard, but have not said anything as to why you think it is silly. Educate me.

Maybe my statement has something to do with lighter weight oil flowing through the oil galleries faster and providing improved cooling that is better for the GT engine. Maybe my statement has something to do with reduced friction that is better for the GT engine. Maybe my statement has something to do with less stress on the GT's oil pump. Or maybe Ford just wants its dealers to stock different weight oils for the Mustang V6 and GT so as to make life more difficult for the parts and service departments.

Your turn.

OK, well I might not know anything about this subject, as I only research and write operational guidelines for engines. You first need to look at this from a manufacturers perspective. The lubrication specs are always determined based on a worst case scenario. You tell the customer to use an oil the will be ok in the most extreme cold and hot situation. However, you must assume the customer is also using the worst oil available. Manufacturers really care about only a few things when choosing a oil weight for an engine.
Engine life - This is usually measured by hrs when testing an engine. Generally 2000 hrs is a nice target when cycling loads. Motorcraft 5w-20 in the mustang is a synthetic blend. Mobil1 is a full synthetic (well sort of). The density between 5w-20 and 5w-30 is exactly the same (around 0.80 kg/l). So, there is only the viscosity at operational temp to consider. The difference of viscosity at operational temperature will be about 14 cST, as SAE 20 is about 50 cST and SAE 30 is around 64 cST. That viscosity will place very little load difference on the oil pump, since the density is the same. This will place a little added load on the CR, crank, and other components, but this load is similar to running the engine at 38 C operational temp versus 40 C. This will cause no damage to the parts. At cold start up, both oils will flow to the bearings in exactly the same way, since the both have the 5w rating. The higher viscosity oil will remain on the bearing for a longer time, causing better lubrication and extended bearing life. However, this is a comparison using decent oils. The SAE 20 and 30 ratings have a decent allowable range. Viscosity differences can go from 10 cST to 20+ cST. Use a decent name brand oil, and there should be no issue. Interesting fact: The most damaging operation in the life of an engine is not full load. Cold start-up provides some of the worst situations for an engine, as the oil takes longer to reach all the internal areas of the engine. Both 5w-30 and 5w-20 are the same on cold start-up.

Engine Performance (HP/TQ) - Here is a place where your viscosity differences affect you. That 14 cST difference could mean a couple % difference in engine output. It will not look as good advertising 295hp vs. 300hp. So, usually engine manufacturers look for the lightest viscosity oil in order to give the least amount of stress on engine internals. This will allow more efficient output from combustion. Ford most likely found that the engine bearings and components would last the full 2000 hr test using 5w-20 oil, and that will give much better power output than using the SAE 30 oil. In a muscle/performance car, the added hp and tq is a major selling point.

Engine Efficiency (BSFC or MPG on road) - The fuel consumption of an engine can be effected by even slight viscosity differences. As your oil gets older, it also gets dirtier. This increases viscosity and explains why you get more mpg when the oil is clean. The SAE 20 and SAE 30 also give different fuel consumption results. When I was with Fiat, we were testing 15w-50 vs 10w-30 in an endurance test. The SAE 50 oil actually raised our BSFC (brake specific fuel consumption) by 5%. That is a big difference. With the Ford V8 already being slightly fuel hungry, dropping the mpg rating to 22mpg highway would not look good. Obviously there are ways to change this with gear ratios and other components of the car, but they are not on an unlimited development budget. Best solution is to get the most out of the engine with your current design.

So, as a summary, you can use 5w-30 oil, but it will not be suggested as it hurts the engine efficiency. It will not destroy your engine, but it will make you burn more gas and result in less power.
Is there a reason to use 5w-30 over the 5w-20? Not really unless you fear your bearings are getting old and worn. The added viscosity will give them a little added life, but you may not even notice.
Is there a reason to use mobil1 5w-30 over motorcraft blended 5w-20? Sure. The full syn will take longer to break down and give proper lubrication for an extended period of time. If you are going to change the oil at 7500 miles anyway, don't bother with the full syn.

Motorcraft does not post statistics on their lubricants, so I was not be able to directly compare. I am not an *******, and I hope I don't sound like one. I have spent a few years in engine development and I get a little frustrated at the comments I hear from people. There were no facts given in any of the previous posts about reasons to use one oil rating over another. Art, even you gave little to no facts to back up what you wrote. I hope I can provide more help on this forum than just function as someone who argues with people. I will share my knowledge of engines and combustion and you guys can share your knowledge of performance parts and resources. Deal?

 

[Art161]

OK, well I might not know anything about this subject, as I only research and write operational guidelines for engines. You first need to look at this from a manufacturers perspective. The lubrication specs are always determined based on a worst case scenario. You tell the customer to use an oil the will be ok in the most extreme cold and hot situation. However, you must assume the customer is also using the worst oil available. Manufacturers really care about only a few things when choosing a oil weight for an engine.
Engine life - This is usually measured by hrs when testing an engine. Generally 2000 hrs is a nice target when cycling loads. Motorcraft 5w-20 in the mustang is a synthetic blend. Mobil1 is a full synthetic (well sort of). The density between 5w-20 and 5w-30 is exactly the same (around 0.80 kg/l). So, there is only the viscosity at operational temp to consider. The difference of viscosity at operational temperature will be about 14 cST, as SAE 20 is about 50 cST and SAE 30 is around 64 cST. That viscosity will place very little load difference on the oil pump, since the density is the same. This will place a little added load on the CR, crank, and other components, but this load is similar to running the engine at 38 C operational temp versus 40 C. This will cause no damage to the parts. At cold start up, both oils will flow to the bearings in exactly the same way, since the both have the 5w rating. The higher viscosity oil will remain on the bearing for a longer time, causing better lubrication and extended bearing life. However, this is a comparison using decent oils. The SAE 20 and 30 ratings have a decent allowable range. Viscosity differences can go from 10 cST to 20+ cST. Use a decent name brand oil, and there should be no issue. Interesting fact: The most damaging operation in the life of an engine is not full load. Cold start-up provides some of the worst situations for an engine, as the oil takes longer to reach all the internal areas of the engine. Both 5w-30 and 5w-20 are the same on cold start-up.

Engine Performance (HP/TQ) - Here is a place where your viscosity differences affect you. That 14 cST difference could mean a couple % difference in engine output. It will not look as good advertising 295hp vs. 300hp. So, usually engine manufacturers look for the lightest viscosity oil in order to give the least amount of stress on engine internals. This will allow more efficient output from combustion. Ford most likely found that the engine bearings and components would last the full 2000 hr test using 5w-20 oil, and that will give much better power output than using the SAE 30 oil. In a muscle/performance car, the added hp and tq is a major selling point.

Engine Efficiency (BSFC or MPG on road) - The fuel consumption of an engine can be effected by even slight viscosity differences. As your oil gets older, it also gets dirtier. This increases viscosity and explains why you get more mpg when the oil is clean. The SAE 20 and SAE 30 also give different fuel consumption results. When I was with Fiat, we were testing 15w-50 vs 10w-30 in an endurance test. The SAE 50 oil actually raised our BSFC (brake specific fuel consumption) by 5%. That is a big difference. With the Ford V8 already being slightly fuel hungry, dropping the mpg rating to 22mpg highway would not look good. Obviously there are ways to change this with gear ratios and other components of the car, but they are not on an unlimited development budget. Best solution is to get the most out of the engine with your current design.

So, as a summary, you can use 5w-30 oil, but it will not be suggested as it hurts the engine efficiency. It will not destroy your engine, but it will make you burn more gas and result in less power.
Is there a reason to use 5w-30 over the 5w-20? Not really unless you fear your bearings are getting old and worn. The added viscosity will give them a little added life, but you may not even notice.
Is there a reason to use mobil1 5w-30 over motorcraft blended 5w-20? Sure. The full syn will take longer to break down and give proper lubrication for an extended period of time. If you are going to change the oil at 7500 miles anyway, don't bother with the full syn.

Motorcraft does not post statistics on their lubricants, so I was not be able to directly compare. I am not an *******, and I hope I don't sound like one. I have spent a few years in engine development and I get a little frustrated at the comments I hear from people. There were no facts given in any of the previous posts about reasons to use one oil rating over another. Art, even you gave little to no facts to back up what you wrote. I hope I can provide more help on this forum than just function as someone who argues with people. I will share my knowledge of engines and combustion and you guys can share your knowledge of performance parts and resources. Deal?

Good info!

On a previous car, I switched from a regular 20W-50 to a "high mileage" 20W-50. I did notice a reduction in burning oil. My understanding is that one reason for this result is that the "high mileage" 20W-50 has the 50 towards the high end of the allowable range. They probably also use a different additive package.

Most of us can not do an analysis of the oil we are using to determine its properties. I can not, so I stick with the manufacturer's specified oil unless I believe there is a compelling reason not to do so. An example would be something such as stated above--a high mileage engine that is burning oil.

You certainly raise an interesting point regarding synthetic oil. For the Mustang GT, a synthetic blend is standard, but the owner's guide says that dino is acceptable as long as it meets the Ford specification. I don't recall reading anything in the Ford literature about full synthetic. That's getting into a somewhat different ball game. And more expensive seats--luxury box. For a car in warranty, I would still use the manufacturer's recommended viscosity, just to play it safe. Others might figure that the chances of engine failure during the warranty period are close to zero, and use other than the specified viscosity. They might think that the engine will last for more miles after the warranty expires if they use a different oil, and they might be correct.

Anyway, thanks very much. I do hope that you post more and share more of your expertise. BTW, you have a deal.

 

[raverjames]

Good info!

On a previous car, I switched from a regular 20W-50 to a "high mileage" 20W-50. I did notice a reduction in burning oil. My understanding is that one reason for this result is that the "high mileage" 20W-50 has the 50 towards the high end of the allowable range. They probably also use a different additive package.

Most of us can not do an analysis of the oil we are using to determine its properties. I can not, so I stick with the manufacturer's specified oil unless I believe there is a compelling reason not to do so. An example would be something such as stated above--a high mileage engine that is burning oil.

You certainly raise an interesting point regarding synthetic oil. For the Mustang GT, a synthetic blend is standard, but the owner's guide says that dino is acceptable as long as it meets the Ford specification. I don't recall reading anything in the Ford literature about full synthetic. That's getting into a somewhat different ball game. And more expensive seats--luxury box. For a car in warranty, I would still use the manufacturer's recommended viscosity, just to play it safe. Others might figure that the chances of engine failure during the warranty period are close to zero, and use other than the specified viscosity. They might think that the engine will last for more miles after the warranty expires if they use a different oil, and they might be correct.

Anyway, thanks very much. I do hope that you post more and share more of your expertise. BTW, you have a deal.

The high mileage oil formulation for Mobil seems to be almost the same as their Clean 7500. The only difference is the high mileage formula has a higher MRV (Mini Rotary Viscometer test) rating. This test shows apparent sheer and viscosity at low temperatures. This would lead me to believe part of the ability of this oil to slow oil burning and leaks comes from the fact that it stays more viscous when the engine isn't hot. I am not really a pro when it comes to oil, though. I mostly deal with the engine side of things. I have had to publish many reports on oil types for our customers. I had a couple months where I had to email the ExxonMobil chemical engineers every other day. They make me feel pretty dumb, but I did learn a ton.

As for voiding a warranty because you use an SAE 30 vs SAE 20, I am not sure that would be possible. As long as the oil is old, the basic oil analysis would probably not tell enough for Ford to say you were not using the recommended oil. I am doubting most service shops would ever perform an analysis to begin with.

The fact that Ford recommends semi-syn, but allows dino, is an interesting point. Decent dino oil can go 7500 miles without breaking down, but I am always weary without taking oil samples along the way. I think that not specifically requiring syn blend is risky on their behalf. My company is a little more careful about that kind of thing, but we sell to industrial applications.

 

[NastyStang113]

I've got to agree with James.

 

[Art161]

The fact that Ford recommends semi-syn, but allows dino, is an interesting point. Decent dino oil can go 7500 miles without breaking down, but I am always weary without taking oil samples along the way. I think that not specifically requiring syn blend is risky on their behalf. My company is a little more careful about that kind of thing, but we sell to industrial applications.

Unless things have changed since the 2007 model year, the oil is to be changed every 5000 miles or six months, whichever is earlier. And the oil, even if dino, must meet Ford Specification WSS-M2C 930-A with API Certification Mark. I have no idea what that specification means.

As to not specifically requiring syn blend being risky for Ford, do you think that dino oil would be likely to cause engine failure within the warranty period? After the warranty period, I don't know whether Ford cares what happens to the engine.

I use Motorcraft synthetic blend. My thinking is that it is better than dino, and doesn't cost all that much more. I have the engine oil changed every six months, which is about 1500 miles for me. I think that pure synthetic is too expensive for my use of the car. I suppose it might be argued that because I usually drive the car only on weekends, the engine could really use the pure synthetic because so much oil has drained into the pan, and that pure syn is superior to syn blend. Whatever.

Oh, no. The Raiders are leading the Jets by 3 points with 8 seconds to go. The Jets go for a field goal, but miss. Hold it. The Raiders had called a time out. So try the field goal again. Make it. Now overtime. :OT:

 

[raverjames]

Unless things have changed since the 2007 model year, the oil is to be changed every 5000 miles or six months, whichever is earlier. And the oil, even if dino, must meet Ford Specification WSS-M2C 930-A with API Certification Mark. I have no idea what that specification means.

As to not specifically requiring syn blend being risky for Ford, do you think that dino oil would be likely to cause engine failure within the warranty period? After the warranty period, I don't know whether Ford cares what happens to the engine.

I use Motorcraft synthetic blend. My thinking is that it is better than dino, and doesn't cost all that much more. I have the engine oil changed every six months, which is about 1500 miles for me. I think that pure synthetic is too expensive for my use of the car. I suppose it might be argued that because I usually drive the car only on weekends, the engine could really use the pure synthetic because so much oil has drained into the pan, and that pure syn is superior to syn blend. Whatever.

Oh, no. The Raiders are leading the Jets by 3 points with 8 seconds to go. The Jets go for a field goal, but miss. Hold it. The Raiders had called a time out. So try the field goal again. Make it. Now overtime. :OT:

Under normal operation, OCI (oil change interval) for the mustang is 7500 miles. 5000 mile OCI is only under special conditions (racing, towing, or extended idling). See Ford mustang maintenance schedule 100-03-1 for all the fun details.

WSS-M2C930-A is a standard that just states the specs for 5w-20 synthetic blend oil. Now that I am reading all the specs, I never see any mention of pure dino oil, so I think it should not be used. I don't see any harm in running dino oil, but your OIC will be less that stated in the Ford manual and if there is an engine failure, they could use that against you. That is assuming they care enough to get your oil analyzed.

 

[Art161]

Under normal operation, OCI (oil change interval) for the mustang is 7500 miles. 5000 mile OCI is only under special conditions (racing, towing, or extended idling). See Ford mustang maintenance schedule 100-03-1 for all the fun details.

WSS-M2C930-A is a standard that just states the specs for 5w-20 synthetic blend oil. Now that I am reading all the specs, I never see any mention of pure dino oil, so I think it should not be used. I don't see any harm in running dino oil, but your OIC will be less that stated in the Ford manual and if there is an engine failure, they could use that against you. That is assuming they care enough to get your oil analyzed.

Thanks for the info on the Ford specification for motor oil and the other information and advice.

I have found differing information in different Ford publications. For example, the wheel lug nut torque specification is different in the Owner's Guide than in the Workshop Manual. I don't know which is definitive.

Anyway, the Owner's Guide says, "Use of synthetic or synthetic blend motor oil is not mandatory. Engine oil need only meet the requirements of Ford specification WSS-M2C929-A (4.0L) or WSS-M2C930-A (4.6L) and the API Certification mark." When I look at the Ford Workshop Manual, I see only Synthetic Blend mentioned for US and Super Premium Motor Oil for Canada (except for the GT500, which is 5W-50 Full Synthetic, as someone already posted).

You cite Ford Mustang Maintenance Schedule 100-03-1 for the oil change intervals. Yet my Workshop Manual states that the Maximum Oil Change Interval (Normal Schedule) is 5000 miles or 6 months (whichever occurs first). The Maximum Oil Change Interval (Special Operating Conditions) is 3000 miles, 3 months or 200 hours of engine operation (whichever occurs first). The Scheduled Maintenance Guide booklet is in agreement with the Workshop Manual on oil changes. What do we do? See how many Ford publications say one thing and how many say something different? Do we decide what to do based on what is stated more often?

I give up!

Raiders win in overtime! :OT:

 

[raverjames]

Thanks for the info on the Ford specification for motor oil and the other information and advice.

I have found differing information in different Ford publications. For example, the wheel lug nut torque specification is different in the Owner's Guide than in the Workshop Manual. I don't know which is definitive.

Anyway, the Owner's Guide says, "Use of synthetic or synthetic blend motor oil is not mandatory. Engine oil need only meet the requirements of Ford specification WSS-M2C929-A (4.0L) or WSS-M2C930-A (4.6L) and the API Certification mark." When I look at the Ford Workshop Manual, I see only Synthetic Blend mentioned for US and Super Premium Motor Oil for Canada (except for the GT500, which is 5W-50 Full Synthetic, as someone already posted).

You cite Ford Mustang Maintenance Schedule 100-03-1 for the oil change intervals. Yet my Workshop Manual states that the Maximum Oil Change Interval (Normal Schedule) is 5000 miles or 6 months (whichever occurs first). The Maximum Oil Change Interval (Special Operating Conditions) is 3000 miles, 3 months or 200 hours of engine operation (whichever occurs first). The Scheduled Maintenance Guide booklet is in agreement with the Workshop Manual on oil changes. What do we do? See how many Ford publications say one thing and how many say something different? Do we decide what to do based on what is stated more often?

I give up!

Raiders win in overtime! :OT:

Sounds like Ford is as bad as my company, since they often contradict themselves depending on what you read. I would say that 90% of the people on this forum drive the car hard enough to warrant the 5000 mile OCI. Personally, I will be changing to full synthetic on my first oil change and keeping the OCI to 10,000 miles.

 

[kevanp]

IMHO what it boils down to is this:

Ford would like to say that we can wait longer for oil changes as that reduces the total cost of ownership. This is a piece of key marketing data.


Changing your oil more frequently will decrease engine wear assuming you prime the filters and use quality product.


So it's your call. Do you want to reduce costs or wear?

 

[NastyStang113]

IMHO what it boils down to is this:

Ford would like to say that we can wait longer for oil changes as that reduces the total cost of ownership. This is a piece of key marketing data.


Changing your oil more frequently will decrease engine wear assuming you prime the filters and use quality product.


So it's your call. Do you want to reduce costs or wear?

Possibly. However, Ford does have to worry about warranty work so there aren't going to do anything unsafe for their motors. We know that when we look at their tuning strategies.

I see no reason why semi synthetic oils can't last 5,000 miles. I use synthetic oils and go 10,000 miles. I've done oil analysis tests and it showed that the oil had a TON of time left on it and was in great shape. If you are so worried about it, go get it done yourself. This is who I use and I have great results with them.

Blackstone Laboratories

 

[raverjames]

Possibly. However, Ford does have to worry about warranty work so there aren't going to do anything unsafe for their motors. We know that when we look at their tuning strategies.

I see no reason why semi synthetic oils can't last 5,000 miles. I use synthetic oils and go 10,000 miles. I've done oil analysis tests and it showed that the oil had a TON of time left on it and was in great shape. If you are so worried about it, go get it done yourself. This is who I use and I have great results with them.

Blackstone Laboratories

I agree. I would use blackstone for personal oil tests for sure. It is the only way to really know what is going on inside your engine without tearing it apart.

 

[kevanp]

Possibly. However, Ford does have to worry about warranty work so there aren't going to do anything unsafe for their motors. We know that when we look at their tuning strategies.

I see no reason why semi synthetic oils can't last 5,000 miles. I use synthetic oils and go 10,000 miles. I've done oil analysis tests and it showed that the oil had a TON of time left on it and was in great shape. If you are so worried about it, go get it done yourself. This is who I use and I have great results with them.

Blackstone Laboratories

I am not so worried about it, simply sharing my noobish understanding of the topic.
I feel it is unlikely that a little lower quality or viscosity oil will cause the motor to grenade below 36k miles.
I do feel that higher quality and a bit higher viscosity oil will extend the long term life of the motor.

I also believe that the reason to change modern oils that withstand viscosity breakdown much longer than older oils is to remove contaminants. The oil may still be in good shape at 10k miles but, is it free from particulate matter? gasoline? water? etc. What color is the oil at 10k? Why?

I subscribe to : using high quality oil and filters and changing at 5k.

I am less concerned with reducing short term operating costs than doing what I can to offset driving my car like I stole it.

I appreciate your sharing your testing lab. I have never tested my oil, something I'd like to try at my next change.
I wonder what % of whoopass they will find

 

[battyice]

So, there is only the viscosity at operational temp to consider. The difference of viscosity at operational temperature will be about 14 cST, as SAE 20 is about 50 cST and SAE 30 is around 64 cST. That viscosity will place very little load difference on the oil pump, since the density is the same. This will place a little added load on the CR, crank, and other components, but this load is similar to running the engine at 38 C operational temp versus 40 C.

The visosity numbers you mentioned are good info, but I would like to point out that they are typical for those oils at ambient temperature on a hot summer day (40C). The viscosity difference between SAE 20 and SAE 30 at a typical operating temperature of 100C would likely be 2-4 cST, depending on the particular oils tested.

 

[raverjames]

The visosity numbers you mentioned are good info, but I would like to point out that they are typical for those oils at ambient temperature on a hot summer day (40C). The viscosity difference between SAE 20 and SAE 30 at a typical operating temperature of 100C would likely be 2-4 cST, depending on the particular oils tested.

Yeah, I read the wrong number. Good point. This shows that the oils are even more similar in viscosity.

 

[raverjames]

I am not so worried about it, simply sharing my noobish understanding of the topic.
I feel it is unlikely that a little lower quality or viscosity oil will cause the motor to grenade below 36k miles.
I do feel that higher quality and a bit higher viscosity oil will extend the long term life of the motor.

I also believe that the reason to change modern oils that withstand viscosity breakdown much longer than older oils is to remove contaminants. The oil may still be in good shape at 10k miles but, is it free from particulate matter? gasoline? water? etc. What color is the oil at 10k? Why?

I subscribe to : using high quality oil and filters and changing at 5k.

I am less concerned with reducing short term operating costs than doing what I can to offset driving my car like I stole it.

I appreciate your sharing your testing lab. I have never tested my oil, something I'd like to try at my next change.
I wonder what % of whoopass they will find

Modern gasoline engines with proper filters are not likely to contaminate the oil so fast, unless there are internal problems. I recommend changing the filter every 5k - 7k miles, even if you don't change the oil. If you get a really decent oil filter, you can go longer. In the end, an oil analysis is the best way to be sure. If you have too many particulates in the oil, you may need to change the oil filter more often. Drop in lubricity would mean the oil needs changed more often. Fuel or coolant contamination will tell you that you have internal issues. Certain metal particulates can tell you when you have abnormal bearing wear. I will probably start getting my oil analyzed regularly with this new car. I want to see how long the full syn really lasts.