View Full Version : oil

04-03-2010, 01:16 AM
does anyone agree with the idea of using 15w40 instead of sae30 or 10w30 because it is a better grade oil.i already did a search and read a bunch of different crap but would like to hear some different opinions.

04-03-2010, 01:56 AM
I agree with using 15w40 all of the time, but then again I'm running diesels. 15w40 is a diesel weight oil. I would only agree to use the specified weight and viscosity of oil that was recommended by the manufacturer.

I wouldn't agree on swapping 10w30 for 15w40. Two different types of oil for two different purposes.


04-03-2010, 02:07 AM
As well as 40 is not going to flow as well as 30. It's 10 viscosity points heavier.

04-03-2010, 02:31 AM
I have used both in my machines, I run the straight 30 in the summer and in the late fall when the temps drop I switch to a 5w or 10w30 so the oil is thinner while it warms up and the motor and pumps don't have to work as hard. Its a personal opinion. I guess it depends on where are you are at in the country.

Richard Martin
04-03-2010, 06:03 AM
The notion that either 15w40 or 10w30 is a better oil than the other is absurd. The viscocity of the oil has ZERO to do with the quality of an oil. Some of the qualities of a good oil are excellent additive packages and level of oil refinements.

Oil viscocity requirements are set by the hot and cold bearing clearances within an engine. Engineers determine the viscocity of the oil so the oil provides the maximum lubricity while using the least amount of energy to do so.

If you want to know why they bother with the energy usage try to pull start a 12.5 Kohler engine when it's 30° outside and it has 30 weight oil in it. Good luck with that. That was the engine I learned about oil viscocity on.

SouthSide Cutter
04-03-2010, 07:41 AM
Its all I have ever run in all my air cooled mtrs. Tillers, pushmowers etc. But its 15-50 Syn Mobil 1. Have a 20hp Kohler with 2000+hrs and no smoke. 11year old 100.00 pushmower no smoke. Remember first number cold second number hot.