My Park Avenue Ultra supercharged just hit 160k miles... it has been using OEM 10w-30 for its life, i am just curious if anyone else has done an abrupt change to synthetic like mobil 1. I would like to switch to a synthetic blend but like everyone else have heard that synthetic is good for high mileage motors because of the protection and also heard it is not good to switch on high mileage motors because the engine is used to the cheap stuff.

what is the year and model of your buick, how many miles?

what oil do you prefer? or have had the best luck with?

I thought the Supercharged engines use 5W-30? Mine does. My L36 uses 10W-30. But anyway, back on topic.
I've heard with synthetic, it tends to leak past gaskets more than conventional. Iv'e never tried it, so I couldn't say.
Mobile1 5000mile 5W-30 in both my Bonneville and Blazer.

I think in like 2002 GM changed their recommended oil to 5W-30, really just a preference thing.

I switched to synthetic about 2 years ago, currently I'm running Valvoline 5W-30 synthetic racing oil as a break for when I rebuilt the engine

I use the Carquest stuff we have at the shop. Exceeds full synthetic standards and comes from the oil refinery an our away in Saint John, NB.

I've been using NAPA (Valvoline) 10w30 synthetic in mine since I bought it with 95,000 mi. It now has over 208,000 mi. No problems here and I run a 7,500 mi drain interval.

I've used Full Synthetic 5W30 in both Bonnevilles and my truck. It seems to get the job done! = )

I use Mobil1 5w30 synthetic. Use it in all my cars.

i use 5w30 synpower or mobil one in my gtp but it has only 55k miles and the previous owner ran synthetic in it

my cutlass i switched over to 5w30 mobil 1 or valvoline synpower at 80k

and the ga i tried a mobil 1 high mileage full synthetic at 120k but it caused it to have more lifter tick so i changed it back to conventional

supertech or meijer brand oil in the correct viscosity. and filters other than FRAM.

~200K miles on every vehicle i've messed with and no engine failures, must be doing something right.

regular valvoline in everything i have never had a engine fail. got 200k on a 2.8 cs and 300k on 3.1gp both of those cars were still getting 32-34mpg when i got rid of them.