Mixing Castrol 5w-30 GTX with Castrol German 0W-30

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Jun 19, 2004
Danville, VA
I wonder if this would be a good combo. I like to mix 3 qt of 0W-30 German with 2 qt of CTX 5W-30. and change it at 5000 miles. Here I am lucky to find 6 qt of 03W-30 and I have 2 cases of 5W-30 GTX and 3 cars to spilt the oil between. Thanks Mark
I'd have no problem doing it. You would end up with a home-brewed semi-syn which had some esters in it. They are both Castrol products so I doubt there would be any additive clash. Go for it!
Most Synthetic Blends are only around 20% Synthetic anyway. Why not put 5 QT of GC in one car and mix it 4:1 GTX/GC in the other? Gene
Put all the GC in your LT1 and give the gtx to your "other" engines [Razz] Ok, ok since I own an LT1, I want to give them the best treatment [Smile]
I think the mix would definitely be inferior to straight GC as you "thin" it out, have less TBN, etc. Why not use the straight GC in the most important vehicle or the one that likes a thicker oil? It won't hurt, but you might be mixing a brew that is inferior to GC or GTX alone. [SPAZ!] Adding GC to GTX might not necessarilly improve it either. This is not how Castrol semi-syns are formulated. You might thicken it a bit but dilute the different anti-wear agents in both.
Yes and if you still are not sure what to do with the GC just send it over to me and I'll put it in my LT1 [Smile]
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