Good comments guys...you're getting the idea
The brand of oil is much less important than how it flows cold, followed what viscosity it runs at ops temp. All of the motors (1J, 2J, 7M) you see in a Supra are designed for a 30W viscosity (SAE grade 9.30-12.49 cst). I use GC (after trying several different oils) because it makes the valve train in my 7M run a lot quieter, flows very well cold, and meets the SAE viscosity requirements the motor was designed for. Plus, it's a Grp IV PAO synthetic oil...for the heat a turbo puts out, that will prevent any problems "cooking oil" (coking) in the turbo at shut down. Syn oils also keep the inside of the motor squeaky clean.
Jay - RP is a very good oil, so don't get me wrong...it will meet your needs. But, as previously mentioned, use the 5W version for the cold flow characteristics. When I look at an oil, I also look at what it was made to do...RP is slanted more toward racing. It is a PAO based oil...the additive package is not as robust in terms of wear additives you'll see in oils designed for street vehicles. For the money, Red Line is similarly priced and is a far superior oil...it's Grp V ester based (same stuff used in jet turbine oil)...you can't get much better IMO. Having said that, you start splitting hairs when you are talking PAO and ester oils...both will perform better than mineral oil. Pennzoil Platinum is an exception (it's a Grp III)...Pennzoil has refined (extensive hydrocracking) it to the point where there is little difference to a PAO and the add pack is superb.
When I look at oil, I look at what it's going to cost me as well...here's my opinions on those that are commonly available:
German Castrol - Excellent oil, superb add pack, good price...thicker than average at ops temp. It appears AutoZone will continue to carry this oil.
Red Line - outstanding oil, superb add pack, but expensive...good for those that want the best and don't care about the $$$
Pennzoil Platinum - Excellent oil, superb add pack, good price, but not a Grp IV or V...it is on par with the GC, but not quite as thick at ops temp.
RP - Excellent oil, but expensive...add pack is not as extensive as the above which will shorten the change intervals. That will cost you more over the long run.
Amsoil (all except the XL line) - Excellent oil (PAO based) with a very good add pack, but expensive. You can only get it from an "Amsoil Dealer" in the US...that kind of marketing keeps pricing on the high side.
Mobil 1 - Excellent oil, good add pack, but not a Grp IV or V. Exxon has not been very open about this actually being a Grp III oil to keep pricing up. That's BS IMO (especially with record profits for the company) and I won't buy it...If I were to go with a Grp III oil, Pennzoil Platinum is superior add pack wise and they make it no secret concerning the base oil.
Any of these oils will go 5K easy between changes...the Grp IV and V oils, 8k easy (watch RP though). Just use a good filter, change it at the 4K point, and add some make-up oil.
Pick any of these and you motor will love you
Consider the cold flow (lower viscosity per the spec sheets, regardless of what the 1st number is on the bottle) and how it performs at ops temp pressure wise (you're looking for 10 psi per 1000 rpm). Higher viscosity oils (i.e. 20W-50) is pretty thick even at ops temps...this gives you higher pressures, but is a result of the resistance to flow caused by the high viscosity. Use the grade the motor was designed for
