Oil viscosity: 5w20 vs. 5w30

[US-1]

You will not see any significant differences between RP 5W-20 and 5W-30. Even on a chassis dyno. There would also be no significant differences in the VVT between the two weights.

 

[94tbird]

i would jsut be worried about the VVT stuff with a different weight oil but in my new motor i wont worry about it as im locking out the VVT completely with new cam phasers and no VVT in the tune

 

[MrClean]

At 1400 miles on the car, I did the 1st oil change (to flush whatever metal shavings from the break in, which inlcuded lots of variable revs, some WOT to 6k, etc). I put 5 qts of RP 5W20, and one of Lucas oil additive. I don't know if it was the oil or the engine just developing more power as it matured, but I'm sure it felt livelier after the change.

At 6000 mi I'm doing the oil change w/the RP 5w20 only.