Everyone's Favorite Subject (Oil)

[lukeADE335i]

Penrite HPR10 - full synthetic 10W50.

Cheap down here as it's Australian oil - good product.

[Bullhead]

I will tell you one thing though. If that LiquiMoly goes on sale again a BA I may buy a couple gallons of it. I have heard a lot of good things about it.

[3vilE30]

I will tell you one thing though. If that LiquiMoly goes on sale again a BA I may buy a couple gallons of it. I have heard a lot of good things about it.

LiquiMoly is some good stuff, look for their mos2 anti friction blends. Probably the only oil I would run if I had a built m20.

[mitchlikesbikes]

i ran 15-50 mobil1 from wally world and beat the living piss out of my car for a summer with no issues. probably going to do the same again this coming year.

[LowR3V'in]

20w50

BUT!!

recently I discovered that is way to thick for cold starts
so probably a 5w40 is more acceptable.
Just have to get an oil pressure gauge and test it out.

[digger]

despite what the 25yr old manual says i would never use 20W-xx ever on an engine that sees lots of cold starts, the oil pressure when cold would be through the roof which typically means you are getting less flow on a cold engine. and you know what they say about when most wear happens.....in any case any differences between oils will take a loooong long time to show up so using an oil for a few years without issues means basically nothing, except perhaps pertaining to cam lobe wear but that's not a viscosity thing.

an oil temp and pressure gauge will go along way to tell you what is good for your application

i also am a fan of penrite

[LowR3V'in]

^so what are you using?

[raudonis]

Autodata specifies semi synthetic 10W-40 for all m20s. Of course this is bare minimum. Full synthetic is always better than semi or mineral. For people bitching about it being an old engine I have 1 thing to say - m20b20 from 1977 and m54b30 from 2006 run exactly the same main bearings and conrod bearings with exactly the same tolerances, go figure.

[estoguy]

With that Castrol Edge 5w50, I've had no cold start issues. It's 5w for the cold starts, but still a 50wt oil. I run it all year. last year, we had an extremely cold winter here in Ontario, and I had no problems. I stick to the following for my start up routine: Start, let car idle up to 2 minutes, depending on ambient temperature. I start off slowly, keeping revs below 2000. Once in 5th gear, I keep the car around 1500-1700 RPM. Now I'm a bit more anal here. I wait until the temp gauge gets to the first thin white tick before driving normally. I know that the "normal" temp range is anywhere beyond the blue, but like I said, I'm anal about it, especially in cold temps.

[slothonaleash]

300k+ mile m20b25:

20w50 castrol dino when it's warm/hot outside
10w40 when it starts to dip below 40 degrees F or so--really helps out with cold starts.
Frequent oil changes

I'll be switching to synthetic after a rebuild! (Amsoil if I can get my hands on it)

I wait until the car is well out of the blue on the temp gauge to go over 1/4 throttle.

[Lugnuts]

Penrite HPR10 - full synthetic 10W50.

Cheap down here as it's Australian oil - good product.

Freshly rebuilt engine. Running Redline 5W-40. Seems to do the job. Don't have much to compare it to.

Thinking I'll switch to Penrite 10W-50 at the next change.

[Kevinl]

Delvac 15w40

[indecline]

After reading some of the informative responses... going with 10W40 Mobile/Royal Purple

[mtnbimmer]

After reading some of the informative responses... going with 10W40 Mobile/Royal Purple

After reading most of the uninformed responses, I'll stick w/M1 0W-40.

[dnguyen1963]

Farm and Fleet 15W40 diesel oil works fine for me...$8 per gal.