Castrol 0w30 or Mobil 1 0w40?
Castrol 0w30 or Mobil 1 0w40? I am currently running Mobil 1 5w30 and I want to switch to a thicker oil weight. What do ya recommend I go with? Stay with the Mobil 1 and use the 0w40 or go with the Castrol 0w30 made in Germany oil?
TECH Veteran
Joined: Aug 2003
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From: Kent WA
I would try the 0w30 German-made Castrol if I could find it... unfortunately we don't have any auto parts stores that stock it here in this part of the country, so I use Mobil 1 0w40. No complaints so far, oil pressure always looks pretty good, although I haven't had an oil analysis done as of yet... 
I have been doing oil analysis since my engine was built. I run Castrol Syntec 10w-40. Its a thinner 40 wt. and also meets the GM 1847 Corvette oil specs. With how high most people spin their LS1's, I'm surprised so many run the stock 5w-30.....not to mention the rod knock issue on some (not all) engines.
TECH Senior Member
Joined: Nov 2001
Posts: 7,234
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From: Mississauga, Ontario
I'm extremely impressed with my oil analysis results using German Castrol 0w30, so I'd have to recommend that one. In fact this oil has impressed the guy who interprets my oil analysis results and he is now running it in his vehicles too! He has been interpreting oil analysis results for almost 25 years now, so if he's impressed with an oil, that says a lot.
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What's the difference and why would we want to run a 0w40? What do you think of a 15w50 Mobil 1? I just installed a much bigger cam LG G5X3, should I switch away from my Mobil 1 5w30 now?? Any advice is greatly appreciated!!!
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Verdad Gallardo TECH Senior Member
Joined: Nov 2001
Posts: 7,234
Likes: 1
From: Mississauga, Ontario
Mobil 1 15w50 is too thick, you're just robbing yourself of HP and MPG.
The Mobil 1 0w40 is good because it'll flow very well on startup, and provides the better protection over 5w30 when the engine is hot. Mobil 1's 5w30 is too thin, that is the problem.
But I still prefer Castrol 0w30 over M1 0w40. But given the choice of just the Mobil 1 viscosities, their 0w40 is the one for the LS1. If their 5w30 or 0w30 were formulated on the high end of the 30wt range, it would be ideal. But since they aren't, their 0w40 is the next best thing. It ends up being a thin 40wt to thick 30wt after a short while anyhow.
The Mobil 1 0w40 is good because it'll flow very well on startup, and provides the better protection over 5w30 when the engine is hot. Mobil 1's 5w30 is too thin, that is the problem.
But I still prefer Castrol 0w30 over M1 0w40. But given the choice of just the Mobil 1 viscosities, their 0w40 is the one for the LS1. If their 5w30 or 0w30 were formulated on the high end of the 30wt range, it would be ideal. But since they aren't, their 0w40 is the next best thing. It ends up being a thin 40wt to thick 30wt after a short while anyhow.
Sweet, I will use the 0w40 from now on, if I can find it at the Autozone's here. They should carry it wherever Mobil one is found I assume? Can the Castrol 0x30 be found in local stores?
Thanks for this wonderful post, no need to take any chances!
Thanks for this wonderful post, no need to take any chances!
Staging Lane
Joined: Mar 2004
Posts: 99
Likes: 0
From: S'West Oh
Originally Posted by SSDude
Go with the German Castrol (GC). It is available only at AutoZone. The Mobil 1 0w-40 is a good oil but it will shear slightly (by design) into a heavy 30wt.
Just curious, but how can you identify the "german" manufactured compared to the other Castrol ?
Why is it only sold @ Autozone ?
What do you mean compatible? Like if you had some Mobil 1 left over in the engine, will the Castrol mess things up? Not sure what could go wrong with a different oil, and how it can cause oil leaks.
Originally Posted by '01PEWTERTA
Just curious, but how can you identify the "german" manufactured compared to the other Castrol ?
Why is it only sold @ Autozone ?
Why is it only sold @ Autozone ?
TECH Senior Member
Joined: Nov 2001
Posts: 7,234
Likes: 1
From: Mississauga, Ontario
Originally Posted by 02WHITEZ
What Is Wrong With Castrol 10w 30
I have been running the Mobil 0W40 for almost a year now. In 3K it uses no oil(Mobil 530 would use 1/4 qt in 3K). It both idles and runs 5psi higher than with the 530, 45/50 psi at idle and 65 plus at 2000 rpm + and right at 70-75psi at WOT. I have not had it analyzed but I like the extra protection in Ga. 90 plus degree summers.
Originally Posted by '01PEWTERTA
Just curious, but how can you identify the "german" manufactured compared to the other Castrol ?
Why is it only sold @ Autozone ?
Why is it only sold @ Autozone ?
TECH Enthusiast
Joined: Aug 2002
Posts: 521
Likes: 0
From: Los Angeles
Originally Posted by C5 Forever
The question is, Is this Castrol campatible with Mobile 1? I don't want any oil leaks.
i mean regular not synthetic 10w 30
about this german 0w 30 is that the best oil for the ls1?
and why is there oil that is the same but different cause of where it comes from
about this german 0w 30 is that the best oil for the ls1?
and why is there oil that is the same but different cause of where it comes from