Howoften should I change my synthetic oil?

Discussion in 'SN95 4.6L Mustang Tech' started by NYStang2002, Dec 4, 2003.

  1. I think I saw that royal purple claims every 6 months and/or 6000 miles but I try to change it before then
  2. lol, i'm the same way. soon as i start to approach the 3000 mile mark i try to find a day when i can get it done coming up. actually bout 900 miles from next change. :p
  3. I used Valvoline Full synthetic or full synthetic with the Valvoline durablend. Now with 75.5k I use Valvoline Max Life. Changed every 3k miles.
  4. I'm a procrastinator so at 3,500 I start thinking about it but I don't do it until 5,000...

    Mobil 1 with a K-N filter.
  5. corvettes come with mobil one and under normal driving GM is recommending once a year.

    i change mine every 250 miles to be safe.
  6. I have almost 27k miles on my car now. I did the first oil change at 1,500 miles, filled it up with 5 qts. of Slick 50 and haven't touched it since ... she still runs like a champ and it feels like I got 50 hp from it too. :nice:
  7. 2500? :D
  8. :notnice: :nonono:

    You haven't changed your oil in 26,500 miles? I can't imagine the sludge stuck in that engine. You better get that thing changed immediately and change it with synthetics ever 3000 for the next 3-4 oil changes or your going to have a screwed up engine.

  9. that must get expensive :D
  10. No, it only has about 25,500 miles on it. I've looked inside one of the valve covers and it's clean as a whistle. FYI, you don't pour in 5 qts. of Slick 50 and replace it every 3-5k miles ... too expensive. I'm leaving it in til I see it start to get nasty, then I'll change it. Another 3k miles and I'll probably change the filter and top it off though ... just to be safe.
  11. Someone is very confused here... :lol:

    Even with synthetic, I wouldn't go past 7,000 miles between oil changes and definitely change out the oil filter every 3,000 to 5,000 miles!

    It's going to be a lot more expensive when your engine takes a dump.

    BTW... Slick 50 is an oil treatment not an oil replacement! Read their website if you are not completely sure about the product you are using. The website says, "6). After Slick 50® Engine Treatment is installed do I still need to change my oil according to the manufacturer’s specifications?
    Yes, Slick 50® is not a replacement for regular scheduled maintenance.
  12. Let me try to lay out some oil life facts:

    The life of motor oil in normal driving on roads is limited by the oil's ability to suspend particulate contaments in it. When there are more contaminants than the oil can keep in suspension, they start settling out and form sludge.

    The rate of contamenant formation is HIGHLY dependent on your driving habbits. If you drive 50 miles on a highway everytime you start your car, you may be able to go 10,000 to 15,000 miles between oil changes without any problems. However if you make lots of short trips, say 2 - 5 miles most of the time, your oil may be at the end of its life in under 3,000 miles.

    In general synthetic oil will have a longer useful life than conventional oil because synthetic oil needs a lower amount of Viscosity Modifiers. VM's are used to extend the oil weight range. The greater the range the more VM's are needed. The downside of VM's is that they reduce the oil's ability to hold contamenants in suspension.

    Another thing that plays into this is how much oil the engine holds. By today's standards, the 5 quart capacity of the 4.6L is a bit on the low side. The V6 engine in the Lincoln LS takes 6.9 quarts and the LS V8 takes 6.5 quarts. I think the BMW M3 takes about 9 or 10 quarts. More oil = ability to go farther between oil changes.

    One more consideration is time and climate. Even if you don't put a lot of miles on your car, over time the oil will absorb moisture, especially if you live in a humid climate.

    With all these factors and the Mustang GT's 5 quart capacity, a rule of thumb for "typical" drivers, that is those who have a mix of short and long trips and want to keep their engines in good condition, I'd say the maximum change interval is 5K / 6 months for conventional oil and 10K / 10 months for full synthetic oil.

    Sooner is better but for most people if you're changing your oil more frequently than 3,500 - 4,000 miles, you're probably wasting your time & money.

    But again if you do lots of short trips, you should change your oil sooner, but if you make lots of long trips you don't need to worry too much about pushing those #'s a bit.
  13. Right now I have some Mobil 1 synthetic 0w-20 getting ready to go in w/ a Mobil 1 oil filter. This will be my first change from the motorcraft oil and filter to the Mobil 1. It makes sense to run the same brand filter with the same brand of motor oil your using. If youre using a synthetic like Royal purple that doesnt make filters, then just use a K&N Gold oil filter.
  14. what kind of filter is that?

    just never heard of it before and trying to get away from fram since I need a good clean oil system since my car injects oil into the intake manifold

    how much do they cost and are you really sure theya re that good?

    not trying to offend you but I would like some information on that
  15. I run Amsoil XL-7500 in my wife's Taurus and we change it every 6000 miles with filter changes every 3000 miles. I also run Amsoil 5w30 in my F-150 and also in her comutter car (Festiva) and we go as much as 9000-12000 miles between changes (but they get new filters and topped off every 3000 miles also.)

    My Mustang gets changed every 3000 miles (Amsoil also). But I am running a Vortech S trim on there also..
  16. Anyone who says change synthetic oil at 5000 miles is just guessing (and wasting money). The ONLY way to tell if oil has deteriorated is to send out a sample to a lab.

    Synthetic oil can last much longer than conventional oil. I switched the GF's Explorer over to Amsoil and change the filter every 12.5k, oil and filter every 25k - never ran better.

    My friends PSD Excursion followed Amsoil's recommendation to the letter - bypass filter, change small filter every 7500, both every 15000 and send out for a sample. His oil lasted for 93,000 miles this way being tested constantly. He also sent samples to independent labs to verify Amsoil's results and they came back the same.

    Don't fall for the trap...a *GOOD, QUALITY* synthetic can go much longer than 5000 miles. If you're not going to use Amsoil, use Mobil1.
  17. Wix filters can be found at NAPA....whatever you do, don't use Fram - they suck, they clog and I've seen more than a few blow up (and had one). Wix also makes Amsoil's filters for them I believe.