Which is best to run in a basically a stock LS1?The car is driven from April thru November and stored thru Chicago's Winter.I spoke with an Amsoil rep and he suggested 0w-30 synthetic.I 've always run 5w-30 synthetic.

 

At operating temp, there's no difference between the two (both 30 weight). It's when the oil is at it's coldest that the difference is seen. The viscosity of oil changes with temp. When oil is colder, it is thicker. The higher the number, the thicker the oil. So, the 0w will be slightly thinner when it's cold, which means it will pass through the motor and get everything lubed up a little easier. The difference really shouldn't be that great. Personally, if you're not driving the car in the harsh weather, I say stick with the 5w30. That's what was spec'd for the motor. If you lived down in Texas and never saw cold temps, I'd say 10w30. Or if you drove your car through the winter, 0w30 for the colder months. Just my $0.02...

As for your choice of synthetics, I'd say...look into Castrol Syntec. I always hear good things about them. My rear-end guy had a little misfortune (metal shavings in oil) with Amsoil and I've steered clear of them because of it.

 

I've heard good things about the German castrol. Good luck finding it though.

If you want inexpensive and yet still good. Go to Walmart and get some of their SuperTech Synth. Its inexpensive and is really Quaker State Synth.

I've switch to it and have not experienced the oil usage that I did with Mobile 1.

 

I get the black bottle castrol syntec from walmart. $24 for 6 quarts.

 

Switched from Mobil 5w30 to German Castrol and oil consumption is lower.
make sure it says Made in Germany on the bottle or do not bother with quasy sinth that the rest of Castrol olis are.

 

i have run all the oils and dyno tested most synthetics except the new german oils. amsoil was the best followed by mobil then came royal purple, valvoline and the rest were close. most oils outperformed the stock by at the worst 5 hp. i like the amsoil personally. i was a mobil gut till i swapped and got better fuel mileage and hp with amsoil. most synthetic info is at performanceoiltechnology.com check it out.

 

Id never use quaker state, iv seen to many motors that used quaker, state be coverd with sludge with only 45k miles or so.

I use castrol syntec.
Edit: forgot I was in ls1 section, but still should be helpful.

 

thats probably because quaker state "full synthetic" is not really synthetic. some legal loop hole they discovered allowing them to win a case against Mobil in court, giving them permission to calling their dino oil synthetic.

Mobil is one of the only true synthetics left.

 

Most "full synthetics" in North America aren't. Mobil 1 has even changed their formula and isn't anymore either, IIRC. They're both group 3, again IIRC.

I've actually heard the same sludge complaint about German Castrol whish is European spec synth and thus full synth. I think some of that is people not changing filters like they should.

 

group 3 is a good base stock but not 100% man made. good oil but not full synthetic. cheaper price is a plus. amsoil is still 100% synthetic. who can argue with up to 25,000 mile intervals

 

If amsoil was more readily available that would be different IMO.

How often are you changing the filter per oil change?

 

Mobil 1 is 100% full syn & works great. They also have some semi-syn.

 

I also read that Mobil 1 synthetic was 100% synthetic, but that was 6 months ago. Amsoil has done a lot of very aggressive marketing aimed at putting down Mobil 1, claiming in their own tests that their oil lasts longer.. Engine oil analyses doing by a lay person on an ls1 camaro suggested that Mobil 1 5w30 maintained its viscosity for longer than amsoil, but that was one test by one person. He checked the oil every 1k or so for nearly 20k miles.

 

I know at least Mobil 1 EP is group III.

 

Several studies posted by oil junkies on some of the boards show that Mobil 1 seems to be on the thinner side of 30-weight oils. I'll stick with my Castrol Syntec.