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

md1 LT1 · Jun 23, 2004

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

pbm · Jun 23, 2004

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!

Gene K · Jun 23, 2004

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

cweed · Jun 23, 2004

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]

haley10 · Jun 23, 2004

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.