Best oil weight?

[Eric]

The prior owner of my 05 used Penzoil full synthetic 5w30. I have never used full synthetic but was wondering what weight I should use, 5w30 or 10w30? The weather in CA is very mild so temperature extremes are rare.

 

[06EXP]

You would be fine with 5w30 or even 5w20, but I use 10w30 in my 99 5.3 just because it has 125k on it and don't want to take a chance of a lighter wieght oil leaking. Also, I use Mobil1.

 

[tonydiv]

I switched to Valvoline MaxLife full synthetic several months ago. For the winter I used the regular 5w30 but I just decided to try the 10w30 for the summer.
As above, my truck has 120,*** miles on it and I'm sure that some of the clearances aren't quite as close as they once were.

 

[KWT2000]

i use valvoline full synthetic 5w30 with 232,*** on the clock and in 5k it doesnt use a court

 

[Eric]

My engine has 46,000 on it and I was going to switch to Mobil 1 as I hear good things about their product....and Costco has it on sale $23 for 6 quarts. I went with 5w30 but was ondering if I should have gone with 10w30. Sounds like I will be ok.

Thanks!