WORST Oil Mixes, by Car Owners

[HangerHarley]

Some of us may like to mix certain Oils( Half a sump of one, half a sump of the other, etc) to try to blend the best qualities of an Oil. Examples i can think of:

1) MaxLife and Synpower (?)
2) Different grades of M1 - ?
3) Grade-mixing, of same kind.. if one wont fit all.
4) GC and Normal C Syntec (Castrol, for viscosity beyond a thick 30.)

What would some of the worst, worser, and dumbest mixes be? Surely everyone agrees on Lucas, i am pondering what it is supposed to DO (surely we have all seen their gear display) and that may be on a list of worst mix. Maybe Mixing Conventional and Synthetic on the same sump is a no-no, though manufacturers do it in their blend.

Candidates?

 

[d00df00d]

A long time ago in a galaxy far, far away, I mixed 5 parts conventional 10w40 oil with 4 parts Lucas Oil Stabilizer for use in a manual transmission. I couldn't find the right gear oil locally, and I wasn't about to shell out for Amsoil for a gearbox that was leaking like a sieve and only a few days from being replaced due to failed bearings. That experiment is what initially led me to BITOG.

Shift quality was really nice and it did reduce the horrible noise from the dying bearings, but I don't for one second believe it was good for the transmission.

 

[Quattro Pete]

My take is that by mixing anything, you are just making both products worse, so I don't mix. There are so many great oils out there, I just don't see the purpose of creating additional frankenmixes.

 

[crw]

Call me crazy, but I mix good quality oils in the engine all the time...

A had an F-150 that had the old style 3-speed + granny gear manual transmission. At the time it was well known that the Mazda sourced 5-speed used ATF in the manual transmission. Well, I bought the truck, it was a pain to shift, always grinding... I went to change the fluid and found that the PO had put ATF in there! Sigh...

I changed it to the proper gear oil and the shifting improved, although I think some damage had been done.

 

[pidster]

I prefer not to mix, but in rare cases it's beneficial. The one I can think of is the classic Redline MTL and MT90 mix in Toyota manual transmissions(and I think some other Japanese this works in. Improved shift quality by an astounding amount in my old Tercel. It was pretty worn out and not so easy to shift anymore on any conventional or synthetic 75w90, including straight MT90. The blend, made it feel like new. Put it in my Mom's Corolla as well, not as worn out and less improvement but definitely an improvement.

Engine oils, I'll mix if I have to use up leftovers but I cut it to a shorter OCI if I do it. I never PLAN on mixing motor oils.

 

[chromecrow]

Once upon a time I knew a guy that had some sort of small honda. The motor had spun a rod bearing and smoked. I helped drop the pan and replace the ONE bearing. He then proceeded to install one Qt of engine restore. One Qt of "motor honey" and a Qt of some other "additive". That left room for ONE Qt of oil. He drove away happy!

 

[REDDOG]

Originally Posted By: chromecrow
Once upon a time I knew a guy that had some sort of small honda. The motor had spun a rod bearing and smoked. I helped drop the pan and replace the ONE bearing. He then proceeded to install one Qt of engine restore. One Qt of "motor honey" and a Qt of some other "additive". That left room for ONE Qt of oil. He drove away happy!


I think we found our winner!

As above I've mixed to use up odds and ends but I don't mix with any intention of improving on things.

Over the years here one mix I've noticed that always seems to yield good results in used oil analysis is Mobil 1 and PP.