Oil weight ... what to use?

[gktbay]

Good morning!

Need some opinions on use of 20w50 dino oil vs. 10w40 dino weight.

5.0 runs 180-ish degrees, has average blow-by characteristics and has 100k+ miles on motor.

Do chime in on synthetics and dino oil brand recommendations, please.

Thanks to all.

 

[MTLBLKNOTCH]

Mobil 1 20w50 or 15w40

This is what I have been using for the past few years now and it's great.

Sean

 

[gktbay]

When if so, do you use the different weighs?

 

[HISSIN50]

M1 synthetic is 15W-50 and 10W-40 last time I got some.

Simply stated, you want to run the least viscous (thinnest) oil that maintains pressure at all times. Hot idle is generally when pressure drops the most. If 10W-40 works well for you, I would not necessarily step up to 20W-50.

I'll say that I live in Arizona and on the '88, I do run 20-50 in the summer and 10-40 for the other 6 days of the year. Seriously, I run 10-40 when lows start to get below 75*F.

Good luck.

 

[Bigstang1]

I Run 15w-40 motorcraft diesel oil in my 190k motor and it works great. Diesel oil is a much better quality oil and must put up with greater torture during testing before failing than gas oil.