I have a 98 ws6 with 40k miles and minor bolt ons I have oil consumption problem,s and I have read and noticed my 5w30 M1 is thinnning quickly, I want to know if the 0w40 GC is what would be better to run or a Royal Purple product, anyone with their two cents would be greatly appreciated.

 

have you considered a catch can, upgrade your pcv valve, the oil your using is fine, I run it my self, others use the german castrol but is sometimes is hard to find. Is far as the purple, some swear by it, personally I would never run it, seems like a gimic to me, but I have never tried it so I really can not be a valid opinion as to its performance. But most that run it use the race blend 40, which I am told is the equivelent of a 5w-40.

 

The German Castrol is actually a 0W-30 that is much thicker at operating temps than Mobil 1 5w-30, and will not thin out/shear down as badly as the M1. The problem (as stated above) is finding it. I've never actually seen any despite actively looking for it everywhere I go.

The Royal Purple RP41 is actually like a 10W-40 and is a very good oil which many have used with great results. I just wonder whether or not it has enough detergents in it to use long term on the street. Since it is labeled a "race oil" which typically have no detergents added to avoid foaming at ultra high revs.

 

I run the RP 10w-30, not the race oil. I have not had a problem yet with it.

 

AMSOIL 5w40

 

Mobil 1 5w-30 This oil is tooo thin!

Royal Purple 5w-30 This oil shears too easily;

GC 0w-30 This oil is built just right for the LS engine.


PS. GC is 0w-30 and not 0w-40.

 

x2 exactly.

 

RP 5w30 but going to use 10w30 next time around.

Royal Purple is good stuff or Amsoil.

 

i used to run rp in my 91. then used a Q synthetic, didnt' notice much diff between the two. but a huge diff going from conventional to synthetic..

 

110K miles...cammed...sprayed...my car has always ran GREAT on Mobile 1 oil. My cars will see nothing else.

 

AMSOIL 10-40 got rid of all my oil comsumption. i didn't have any oil issues before the cam but once it was in it started eating up M1 10-40. Amsoil solved that and quieted down my valvetrain. AMSOIL

 

85K miles on Mobil1. Tried German Castrol but didn't see any benefit. Oil consumption was still very little. Went back.

Dont forget a catch can. They used to be cheaper though.

 

Mobil 1! I'll use NOTHING else.....

 

use the moble 1.

 

Cause your oil filler cap said so?

Andrew

 

Mobil 1 5W40 here......

John

 

M1,RP, either way 5w 30 is just fine, I heave seen many of cars making alot more power than street cars use it and have no sheering issues. If your having sheering issues you may need to do more than thicken your oil, thinner oil = faster moving parts less weight on internals. And 5w 30 is perfect for the LT1,LT4,LS1,LS6,LS2,LS7 !!!

 

Mobil 1 15-50
I like the thicker oil.

 

I used to run Royal Purple 5w-30 and had no problems. I recently decided to try Mobile 1 0w-40 just out of curiosity. No complaints yet.

 

when i got my car i put m1 5w30 in it and it was noisey and seemed like it wasnt enough for the motor and i was consuming tons of oil like a quart every 1k mi, i then swtiched RP 10w30 and it got better not as noisey and less oil consumtion,but lately i swtiched to the GC 0w30 and im sticking with it. tests have shown its the best to use and ive gone down to about only 1qt every 3k mi. the enigne runs quiet and im happy sense its cheaper than RP,i also picked up 2mpg with it , we also had the exact issue in my gf monte carlo ss. m1 5w30 noisey in the motor and a drop in mileage. GC 0w30 problem solved and much smoother running afterwards no lie. GC is the best and im sticking to it, m1 sucks its to thin, the 5w40 is suposed to be ok but im not useing it.