Just for the record - Mobil1 does not come in 20W-50! It's available in 0W-30, 5W-30, 10W-30, 0W-40 and 15w-50. Ford recommended 5W-30 for my crate 351W, while Porsche recommends 15W-50 for my 944.

Neither recommends the various "snake oils" which seem to be popular with the Cobra guys.

Bob

Oil
 

My engine builder had multiple National Wins sine the 60'S and has done extensive research into oils. He would be more technical and indepth of about what I am about to state.
He used to swear by Mobil 1 before they changed the formula a few years ago and take out the "Good Stuff". If you have noticed the bottles changed again in the last 8 months. Well, they put the good stuff back in and he swears by it again.

But, But, But...
If you are running a solid lifter cam big block, his number one choice was Pennzoil Racing 25W50. If you smell it you can smell the stick of the additive. The only other oilf that supposedly has it and the stinky smell is the Unocal Nascar 76 Racing 20W50. He never advised synthetic and said he would only stand by the motor if I used the oil he wanted.

Wellllllll,
CSX 4027 ran over 1500 track miles and never missed a beat, In fact, the new owner is still running strong and only using the Pennzoil 25W50.

Be it luck or coincidence, I go by his theory.
I ran 12.1 : 1 581Hp 522lbs torque and chipped at 6800

If you want to contact him to pick his brain be my guest
Cerrali Competition Engines 973-742-4972

Amsoil Oil comparison tests
 

CSX4027
What you say sounds sensible Mobil 1 is readily available everywhere, I think Pennzoil Racing 25W50 is available here in NZ!

I have been reading up on Amsoil, and have used some of their oils in the past when I bought a car already on it, that car still seemed to need a top up after 6500 miles, and I put the same car on Mobil Super 10-40 mineral and it does 8500miles before it needs a top up! They claim that their oil is better than every other oil on the planet, the tests are with Amsoil 2000 20-50 Racing synthetic oil, which they say has all the additives for road use, below is some oils from Amsoils comparison this can be viewed at

http://www.tnsynthetics.com/dyno.htm

1)_____ AMSOIL
2)_____ BP Visco 5000
3)_____ Mobil 1
4)_____ Mobil 1 (difference being price)
5)_____ Hi-Tec HTO
6)_____ Shell Helix Ultra
7)_____ Royal Purple
8)_____ Castrol R
9)_____ Castrol SLX
10)_ Torco”
synthetic etc

I find their claims are becoming unbelievable as everything they do or have ever done is better than everyone else, including major oil companies, and companies like Castrol that have invested millions into research etc. How can their oils be always better in every facet of the testing than all others, I find it could be Bull****! - and would be interested in others opinions on this company claims and products, as they are always naming all the other oils that are inferior to theirs.

Ant

I don't know, I'm not a big fan of synthetics myself. Good comment about "racing" oils, wouldn't use them for a street application at all.

I think the MOST important thing is this:

Stick with a good quality brand name you like and change it often. BUT DON'T mix and match brands in the same engine, even after an oil change! Get ONE, stay with it! Some combinations of motor oils combine in a "bad" way and create problems. Like a bad combo of "prescription" medicine, you just never know what the wrong combo might be!

Ernie