I use the same as Dan, Mobil 1 High Mileage Full Synthetic and a Mobil 1 Extended Performance filter. I buy both in bulk to bring the price down.

I have a 98 Olds LSS with 260,000 miles and have used nothing but Havoline 10w-30 with an AC oil filter (PF47). I change it every 3000 miles and change the oil in the supercharger once every year.

You can start running GM'* new dexos 1 oils. It'* made by Mobil 1. Step dad is is able to get at just over $4 a quart from the dealer.

Your price might be different though.

I use 10w30 synthetic blend. not a full syn. and Im partial to the OEM replacement AC Delco filter. You could also use a 5w30 if you are in a warm climate. I need the 10w30 cause my lifters make a ton of noise when its REALLY cold out.

You seem to be confused about the cold viscosity. 5w-30 is thinner at very cold temps (around 32 and below) than 10w-30, thus is suited for colder climates. It will pump better when cold, reaching the lifters quicker.

10w-30 doesn't have as great a viscosity spread, so is less likely to break down and go out of grade during use-- this is likely why GM specifies this grade.

Also, nearly all current AC Delco filters are made by the same company that makes STP, Supertech (Walmart), and many other filters. Most use an "E-core" design that is shared among the various brands. There'* nothing special about them, but if it helps you sleep better at night...

I have lucas oil in my car right now and after 7000 miles the DIC still says 20%.

I use Fram extra guard (not the regular Fram ; the extra guard has a better build and has a pin in the bottom to make sure oil splashes everywhere in the filter by itself) with Pennzoil high mileage oil and my 240k kms engine runs with no clicks or pings or metallic noises or anything anoying at all. I put between 600-800 kms on the engine per week.

I also put a quart of ATF when I'm 1000km from the oil change.

Oh, I also have a good trick to keep my engines healthy : I don't beat them, I wait for them to be hot before using the supercharger, I don't turn off the engine right away if the temperatures high from X, Y or Z reason.

One musn't forget general mechanical engineering rules quite apply to gasoline engines!