Quote Originally Posted by markis View Post
http://www.alibaba.com/product-free/...Lubricant.html - "Synthetic based engine oil" and of course me working as a mechanic using this same oil and seeing how it performs means squat.? are you a mechanic?

EDIT: upon a thorough search. i see mixed opinions about magnatec. alot of people claiming its shit and alot of people saying its great. im just going off what ive been trained. so personal experience tells me that its a fine oil and copes with heat just fine.
I have used it and I have to say that Magnatec 10w-40 breaks down in 7000km of normal combined driving (at which the engine runs rough, I repeated this over 3 oil changes for 18 months), which is typical of a mineral oil. Even Mobil's Synth S (now Mobil 2000) lasts longer than that and keeps running smoothly.
Quote Originally Posted by markis View Post
then again ive used all castrol oils in my GTRs and silvias and evos. 10w-60 took heat like a champ., 0w-40 was smooth as silk good economy didnt break down. the 5w-30 was shit house. caused solid lifters to chatter within 500kms on the gtr. was switched out with 0w-40. and out of my years of experience and advice from regular drift and track junkies i still use ROYAL PURPLE.10w-40. $80 a bottle. it takes heat better than castrol will ever do and yielded the best result in that commodore oil analysis years ago.
Castrol calls that 5w-30 a fully synthetic oil and you have experienced it to be anything but by not being able to withstand the heat in the GTR. That is what I would expect to happen since it is only a "Group III synthetic" which is actually a hydrocracked mineral oil. It protects reasonably well like a synthetic when fresh but breaks down as quickly as a mineral oil under heat and pressure. That is why I always take Castrol's marketing with a pinch of salt, same for the reason why I don't consider Magnatec 10w-40 a semi-synthetic and the Edge 5w-30 a true synthetic because they just are not.