What motor oil do you use for a 1970 IIA?

[luckyjoe]

A lot of good info here. Being that the 2.25 is a rather dated design, it has been my experience that a good 25W50 is closest to what would have been available 40-50 years ago. I've run it year-round for the past 10 years. I have a nice tight 2.25p, but wouldn't run anything 5Wxx or 10Wxx in it.

This year was the coldest Winter we've seen in a while, and although 25W50 is considered thick, I had no trouble hand turning the engine the few cold mornings I tried it - granted, we don't see much below -5F.

I have been eyeing the Rotella 15w40 though, and may try it next change.

Tom P.

[TedW]

A lot of good info here. Being that the 2.25 is a rather dated design, it has been my experience that a good 25W50 is closest to what would have been available 40-50 years ago. I've run it year-round for the past 10 years. I have a nice tight 2.25p, but wouldn't run anything 5Wxx or 10Wxx in it.

This is always an interesting discussion, and reasonable people can disagree on what's best for our sleds.

That said, Jac04 tells us that Turner recommends 10W40 for his new long block.
I'd say that their opinion carries some weight. After all, in addition to really understanding these engines it seems to me that they have a strong economic interest in having them last.

[jac04]

I have a nice tight 2.25p, but wouldn't run anything 5Wxx or 10Wxx in it.

Any particular reason? There are certainly many 5Wxx or 10Wxx oils that provide excellent low temperature pumpability while maintaining more than adequate high temperature viscosity. When an engineer selects an oil, he/she determines the viscosity required for actual operating conditions (higher temperature in our case). Unfortunately, as oil cools it becomes more viscous. This "excess" viscosity does no good, hence the use of multiweight oils. The ideal oil would have a single viscosity independent of temperature, but that just isn't possible.

[I Leak Oil]

I've used various brands of 10W40 for 14 years now. Hasn't exploded, disintigrated or failed yet. Just put something slippery in it and move on. It's not a Ferrari.

[stonefox]

I personally make my own from an old family recipe:

2 parts canola oil
1 part seasame oil
4 parts yak fat -hard to get these days so you can sudstitute Muskox fat(good for cold starts)

[I Leak Oil]

Sean, I believe that recipe is designated as 2NY14.

[gudjeon]

I have found that some 5wxxx it 10wxxx are great in the cold or when they are put in new. After some time, even the best brand thins out when the ambient temps get warm. That's why if you go this route, use it for winter. This is the main reason I went to a good 0w50 or the Rotella 5W40 as I was too lazy to change it as soon as it warmed up again. Besides for amount of mileage I do and mostly put-put in the woods, I only change it once a year.

[Lowlandbear]

I use 5w30 in winter and 10w40 in summer, but I live in Maine and the poor thing hardly heats up in winter, even with the front almost completely closed up.

[jac04]

After some time, even the best brand thins out when the ambient temps get warm.

Post up your UOAs, they would be interesting to look at.

[TedW]

http://motorcycleinfo.calsci.com/Oils1.html

Some interesting info here for all you wonky types.