Oil mixing question

[double vanos]

I need the wizards on this boards help. In my 2005 Miata I have been using Castrol Syntec 5w20 with really good results. I would love to use GC in it but I think it's too thick. What if I just put in one quart of GC and the other 3 qts Syntec 5w20? Would there be miscissability problems or do I need to just stay with 5w20 only and perhaps pay a visit to a shrink for even thinking of this? I sit in a straight jacket awaiting your answers......

 

[Triple_Se7en]

In your climate, I would use all GC. Until your warranty expires, just stick to the Group III Syntec 20 weight.

 

[double vanos]

Thanks for posting Al - heck, if you've mixed all those every which a way, I have nothing to fear! Also thanks 777 for responding; as soon as the warranty is up it will be GC all the way! Cheers! DV

 

[RD400]

I doubt there would be a problem. According to my amateur interpretation of calculations using this Viscocity Calculator, you'll end up thickening the oil by about 8% at 100*C and probably still be thinner than just about any XW-30 oil.

 

[Max_Wander]

do you bounce the miata engine off the limiter?

 

[Drew99GT]

Member Ray H had the best used oil analysis on his " mystery " blend, consisting of 5 DIFFERENT brands of various API rated 10w-30s. If that doesn't rid you of the oil mixing heebby jeebbies, nothing will! Mix away, it's fine!

 

[double vanos]

What a great bunch of guys! This is my wife's car and it has a slushbox so, no, it NEVER hits the rev limiter. I think I'll start off with 25 per cent GC and start increasing the ratio by 25 each succesive oil change until I reach 100 per cent. I'll get back and let everyone know how it pans out. Many thanks to all! DV

 

[Al]

There is no problem that I can see. As many know here I have mixed GC, RedLine, Mobil 1, Havoline, Mobil DC, Motorcraft, Tropartic and done UOA's with no problems. Of course I might have a big slug of undisolved stuff in the bowels of my engine somewhere, but I doubt it.