Engine Oil Type--Why Different?

[Stubbyie]

Question to the Forum concerning engine oil used in Kubotas.

Let's compare two Kubotas.
I'm going to omit model numbers for the moment and ask for general responses.

One machine is 2002, one machine is 1995.

Both tractors are 3-cyl and are essentially the same engine per specs.

The 1995 (1,500-hrs) calls for 10W-30 oil.

The 2003 (500-hrs) calls for 15W-40.

Other than the Owner's Manual saying so, why the difference?

What changed in the interim?

What are your thoughts on "upgrading" and using the same oil in both machines?

Which oil would be "better" yearound in temps ranging +115F to -15F?

I welcome all knowledge insights experience and comments.

 

[cmorningstar01]

Below is a link that gives a bit of understanding to Multi-Viscosity oils.

http://members.themotoroilevaluator.com/index.php?id=144

 

[Bulldog]

All of my Kubotas have been rated for either weight oil. Unless a person is in a climate that would require the heavier 15w40 weight oil all it will do is make your engine consume more fuel. In most cases the 10w30 is the better choice. Myself, I prefer using 5w30 synthetic. It allows for easier cold start up in the winter, cooler summer time temps and a substantial increase in fuel economy.

 

[LT1Pat]

Oil weight has a lot to do with the engine tolerances. The more clearance there is around a bearing the lower the oil pressure is requiring a higher weight to compensate. Pressure is simply a resistance to flow and since the higher weight oil can't flow as fast the pressure will be higher. I would probably base which oil I use around what my oil pressure is... If the oil pressure seems too low try a thicker oil.