5w30 vs 10w30
#7
RE: 5w30 vs 10w30
yeah my truck calls for 10w30 so i think ill stick with that. i was talking to someone who says they dont like to switch oil brands too often but im taking my truck to juffy lube for an oil change pretty soon. you guys think it will be fine if i switch to a synthetic such as mobil or royal purple from the conventional ive been using?
#9
RE: 5w30 vs 10w30
Once you use conventional you can't use full synthetic oil only partial. Once you use conventional oil it swells the engine gaskets. Using synthetic afterwards will cause these gaskets to shrink to the point where they no longer fit tight between the metal parts and now you have leaks. So conventional or half and half only.
#10
RE: 5w30 vs 10w30
I use valvoline 10w40, gm just wants you to use the 5w30 so their mileage rating are better, same reason they cut the skirts on pistons for higher mileage.
Yet now gm engines have piston slap.
friend has used 20w40 in his 350 engine and has 314K miles. so it must be good.
Yet now gm engines have piston slap.
friend has used 20w40 in his 350 engine and has 314K miles. so it must be good.