97 LT1 with 105000 miles. i run mobil 1 10w30 but i was wondering if 5w30 would be better. my motor has a little knock right when you crank it up when it cold but theres no engine noise after it warms up. thanks!

 

I am no expert, but I would be hesitant to change oil weight on a motor with that many miles. Additionally you would be switching to a thinner oil, if any of the seals are questionable the thinner oil may cause them to rear their ugly head. My SS has 44k miles, and I wouldn't change from the Royal Purple 5W/30 it has always used; not that I would want to.

Find out whats causing the knock, if a change in oil weight silenced the noise, that would seem more like a band aid to me and not actually resolving the issue.

 

Shouldn't be a problem. 5W-30 is only thinner than 10W-30 at 0*F. Once the oil warms up (212*F), they are both "30" weight (particularly true of synthetics, compared to regular oils with their viscosity extenders). The knock at low temps could be due to inadequate oil circulation. The "5W" might help get the oil circulating faster in cold weather.

 

especially if you run synthetic you will have no problems.

Bret