i live in tx and was wondering which would be better?

any ideas...

 

What have you been using?

Ideally 5w-30 synthetic would be best.

 

Use what the manufacturer recommends but in synthetic.

 

manuf suggests 10w30 but i hear alot about people using 5w30

 

what does the number say on your oil cap? mine is 5w30 so that is what i use

 

I live in Wisconsin and run 10w 30 in the summer and 5w 30 October through April when its cold. My cap says 5w 30 but I like the thicker oil in the summer. I always run mobil 1 and have had great luck with it.

 

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?

 

i use royal purple 5w30 and have had no problems from either of my 2006 silverados

 

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.

 

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.