badmix
1/2 ton status
Any real benefits to switching to thicker weight, I'm in Florida. Truck is 84 K5 w 181k on odo and leaks oil.
CK5
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Swit10w40 for 20w50
- Thread starter badmix
- Start date
Personally the heaviest I'd run is Shell Rotella 15w40. Even being in warm climate, I wouldn't want too thick at cold temps, which is the first number.
Rotella 15w40 in every truck all year long
78 GMC Jimmy
1/2 ton status
Go with the GM recommendation. What ever it calls for. If ya got leaks, throw in some AT-205.
Personally for those old engines with more than 150k miles I use 20w50, it cuts down on leaks and burning oil.
Been doing this for 35 years and my engines have all had long lives.
I would not use this oil on newer engines 2000 and up
I just swapped my big block to rotella 15w40. The 10w30 had 55 psi cold but would drop off to the low 20's and even 18psi hot at idle. I was getting some valvetrain noise. The 15w40 holds at 28psi hot now idling and is still 55 to 60 cold. I think the engine should have been fine with 10w30, it was designed for it. I am happier with the pressures with the 15w40. This is a fresh engine. I had thoughts of a bad oil pump with the lower idle pressures on 10w30. Still not totally decided on the pump with 28psi idling hot with 15w40, I would have been happier seeing it in the 30's. Trying different oil is lots easier than swapping a pump.
78 GMC Jimmy
1/2 ton status
Ya, changing the oil weight to help the oil pressure is a reasonable thing to do. I would stick with OEM recommended weight otherwise.
pressure is resistance to flow. If your pressures are high the oil is not flowing. You want flow over pressure. As long as you have some pressure at idle, and it increases @10 psi per 1k rpm you golden.
I think the 30 in the 10w30 is the issue, 10w40 might have done better at hot idle. 15w40 is good stuff either way.
I think the 30 in the 10w30 is the issue, 10w40 might have done better at hot idle. 15w40 is good stuff either way.
Viscosity is a resistance to shear
A worn loose old engine isn't going to be harmed by running a hi quality 20W-50 Racing oil. I've ran over a million miles using 20W-50 or SAE with no issues.
Ambient temperature is a critical consideration in determining a suitable weight oil... Florida is warm....
20W-50, SAE 30, both are suitable in a warm environment.
Royal Purple SAE 30 Full synthetic works great year round even cold climates.
A worn loose old engine isn't going to be harmed by running a hi quality 20W-50 Racing oil. I've ran over a million miles using 20W-50 or SAE with no issues.
Ambient temperature is a critical consideration in determining a suitable weight oil... Florida is warm....
20W-50, SAE 30, both are suitable in a warm environment.
Royal Purple SAE 30 Full synthetic works great year round even cold climates.
