I found a good oil...

[CO_Farmer]

At a Harley dealer- LOL.

I've got a somewhat tired YM2500 that still runs well, doesn't use any oil.

What was concerning me most is that when hot, oil pressure was dropping down to 15 PSI or less at 2,000 RPM. I had been using one of the 15W-40 name brands of diesel oil with a can of STP or Bardahl added, probably making the equivalent of a 20W-50 or the like.

I noticed in my manual that Yanmar recommended a straight 50 weight oil in the warm seasons. Never saw any at the local auto parts stores, but Harley-Davidson dealers sell a premium straight 40, 50 and 60 weight motor oil for about $4/qt. Changed to the Harley straight 50 today, made a huge improvement in oil pressure when hot. Never got below 25 PSI while grading the road when it used to drop to 15 PSI or a little less. AND the engine had noticeably less clatter.

In the winter, I'll go back to the multigrade, but I am really impressed with the performance of this straight-grade oil. Just the ticket for the worn bearings.

Now all I need are some chromed straight pipes...

 

[JerryG]

If your auto place sales Valvoline oil, ask them to get you some Valvoline 50w Racing oil. I used it for years in high performance engines with good results.

 

[Dargo]

Before anyone goes nuts, I do own a Harley; but they are not exactly an example of precision engineering. Usually you think of using straight 40 or 50 weight oil in something that has 300k miles on it or 10k hours. The tolerances in the Harley engines, well, they are not exactly the tightest. Besides, the straight 50 weight oil will not leak out where lower weight oils may.

 

[Soundguy]

Before anyone goes nuts, I do own a Harley; but they are not exactly an example of precision engineering. Usually you think of using straight 40 or 50 weight oil in something that has 300k miles on it or 10k hours. The tolerances in the Harley engines, well, they are not exactly the tightest. Besides, the straight 50 weight oil will not leak out where lower weight oils may.

Carquest carries their own brand of the 50w oil too... ( strangely enough.. it is manufactured in the same city as the valvolene oil, and napa oil... Wonder how many refineries are in that city? Hmm..

Soundguy

 

[Egon]

How many leaks has the Yanmar developed with the new oil?

 

[shvl73]

I use straight 50w or 60w if it's hot, in my shovelhead. It definitely wasn't the pinnacle of engineering in it's day.

 

[Hard Knocks IV]

Thanks for the tip CO Farmer I have an old Fiat tractor with about a zillion hrs that still runs good I'll try some Harley oil in it,also my Pasquali tractor
calls for straight 40 or 50W oil in the Summer probably be just what it needs