i have a Ski boat that has a stock 2002 LS1 in it - it calls for 15w40 conventional oil. This is obviously thicker than the 5w30 that is normally called for when in a car.

It has been running M1 15w50 for quite a number of years before I got it. I put 15w40 oil in that last change. Is 15w40 my best bet ? I have read about 0w40 oils and not sure if it has enough HTHS for this kind of usage ?

 

Hi SK, MY advice would be GIVEN AFTER you state your Water Temperature ?
OIL FLOW is what cools the bearing NOT the Oil Wedge thickness.

NEXT, I would ask for a report of Oil Temperature ?

Lance

 

Hi There, I don't know the oil temp but the water temp gauge reads around 175 all the time. I think it has a 160 degree thermostat in it.

 

Boats vs cars. Boats are used in the summer and the throttle is usually either at 0% or near/at 100% so basically you're at full load most of the time and in summer temps so that's likely why they want the thicker oil in the boat motor. However the coolant temps are a little lower, but the constant high load and high rpm is going to build more heat in the oil and thin it.

 

thanks ! that makes sense

 

Yup 15w40 diesel oil! Boats get some high oil temps.