redline is what the cup teams use. i have a buddy that owns a craftsman truck, most of them run 20w50.

but there is a big difference between m1 and redline. m1 is a mineral base stock.

its to thin because its a 10 weight, i wouldnt run a 10 weight more then about 6K rpms with stock sbc rod/main journal sized.

 

Well, I've been using Mobil 1 5w-30 ever since I changed from the Quaker State synthetics that came with the SS from SLP. Since I'm running a 160 stat and not running hot, I doubt that I would have to fret about cooking the dyno oil.

The C 5s recommended using the Mobil 1 syns from the factory; don;t know what flavor they recommend now.

I assumed when I got my SS with the synthetics that it was a big deal and would add performance. Now I don't exactly know why. I am sure that most will disagree with my assessment, but spinning a bearing with less than 7 grand on the tach and you start to look at alot of things a little differently.

 

i got less than 500 miles on it when mine took a crap. Since this is the first i've heard about a 10w being too thin, i'm starting to think this could be the problem. So should you go with some thing like a 15w30 or higher like a 20w50? 20w50 seems too thick in my opinion, but what is everybody else doing?

 

i run castrol or valvoline non synth 20w50 in mine, its significantly thicker when hot then a 5w30, but its still like water at operating temp. they all thin out when hot. after the head/cam install im gonna step up to SAE 30.

the m1 used to be a synth base stock, but they changed it a few years back.

if i were gonna run a synth id run either redline or royal purple.

if its $5/qt and made of a mineral base stock, its a waste of $$$ IMO. and i change my oil so often it doesnt matter.

 

mobile 1 5w30 is too thin. at least thats what ive gathered from a lot of reading. the 30 weight rating should be more of a 20 weight rating. therefor, you are really running more of a 20 weight oil in your high performance vehicle and not giving it the protection it should have. i would recommend mobile 1's new 5w40 rated oil. that should give you a lower startup viscosity than the 15w50 and also better protection during operating temperature. this viscosity will also flow better at the operating temperature than that of the 15w50 as well. this problem has only been identified with mobile 1 oils that i am aware of.

 

So basically its the weight of the motor oil?

 

in texas, in everything but the winter, running a 20-50 or straight 30 isnt a problem. the fact that the thinner oils flow better is ofset by the fact that the thicker oils stay on the metal better when cold and dont overheat and sheer as easily under load.

a 5w mineral base is a 5w mineral base. it doesnt get thicker. the second number has to do with hot viscosity, but not like most people think. a 5w30 is a 5 weight that only thins as much as a 30 weight at operating temp. it thins, i assure you. my 20w50 is like water at operating temp down here. and ive had people who dont know better say running 20w50 is like running gear oil. i guess a lot of people dont look at their oil when the engine is hot or just dont know what gear oil looks like.

you have to pick the oil weight (first number) based on the ambient temp as well as the powerband. here in tx, especially south tx in the summer, i wouldnt hesitate to use an SAE 30. id run thinner in the spring/fall, but even here in north texas i use a 10w30 in the winter only. when we lived in north idaho when i was a kid we used 5w30s in the winter. it depends on the temp.

if i were racing the car in the winter id use a thicker (20w50 or SAE 30) and use a block heater.

 

You obviously need to do more research. 50% chance of spinning a bearing with a cam install? **** happens if you are inexperienced or have a motor with low oil pressure that you are spinning the crap out of with the new cam. I put a 306 in my 94 formula with 142k on it and ran it to 6700rpms daily. I then decided I did not like that cam and at about 153k I put a 305 in the car and still had zero problems with failed bearings. This motor was raced many times and even had nitrous on the car before I cammed it. My buddy put a 305 in his car and had no problems and 30k later put an 847 in his car and the current owner of the car is having no problems. I do not know a single person around me that has put only a cam in their lt1 and spun a bearing! After all, an aftermarket cam should be round just like the stock cam and should fit perfect in the cam bearings. As long as the install is clean and the motor is healthy there SHOULD not be a problem right after the install.