105k miles mustang and oil viscosity 5w20 to10w30?

will this help my engine stop chattering or not recommended?


i used 5w20 synthetic during the winter and would like to know a good viscosity for the summer and high mileage105k miles mustang and oil viscosity 5w20 to10w30?
I highly suggest that you switch to Valvoline MaxLife synthetic motor oil (10w30) and use it year-round. As far as I'm concerned, it's the best oil to use for all fuel injected Mustangs. Switching from 5w20 to the heavier 10w30 will not only provide better protection and performance, it will suppress most if not all of the engine's valve train ';chatter';.105k miles mustang and oil viscosity 5w20 to10w30?
You didn't say what year. 10W-30 for most pre 90's and 5W-30 for post 90's. Good all year round. I put 10W-30 in my 86 Ford and 5W-30 in my mothers 94 Buick. I once made the mistake of putting 5W-30 in my 76 ford (less than 100,000 miles) and one of the lifters got stuck. Had a nasty tapping from the cam hitting the stuck lifter. Drained the 5W-30 and replaced with 10W-30 and a can of engine restore to cure the problem. Lucas is good, but I prefer CarQuest brand Engine Restore.
We use Valvoline 10/30 in all the cars over 100,000 at our shop unless the customer requests other wise. We do repairs and a lube service.


I don't know what you mean by chattering. It may be a problem that has nothing to do with oil. You can try putting a quart of Lucas oil stabilizer in with the oil.