OK, lets turn that around.
What is the benefit to mixing?
I would like to see one verifiable legitimate example where any mixing of any oil provided any legitimate benefit that would be unattainable by any properly spec'd oil right out of the bottle.
Anybody have one?
Otherwise, I write the effort off as an ignorant persons exercise in vanity if they do it thinking they have actually achieved something.
Just hopped in here. Sorry for my rudeness.
I've told this story here many times, but VW put the incorrect oil (VW 502) in my Jetta 1.4tsi, so at great expense, I purchased 4L of MOTUL VAG 508 00 / 509 00 synthetic oil. I had the VW dealer drain the 5W40 Castrol and install the MOTUL. The Mechanics refused, so the Service Writer and I did it. I wanted to see the oil go in , after the last screw up.
Well after just a few minutes of driving home it was apparent the oil was too thin. Excessive engine noise and the motor wouldnt spin up above 3000 rpm. I let it stay for a couple days but I came to the same conclusion. The engine ran fine 1500 > 2500 rpm, but had nothing above that. Gassing up one day at IRVING I checked the oil and it read about a 1/2 L low.
When I got home I check again and sure enough it was low. So the new stuff was burning off. I've seen this before with PAO oils Like M1 EP 0W20 in a Honda. It would soon stabilize. But this didnt correct the hot viscosity issue. I had a litre of M1 0W40 FS reserved for my Generac oil change collecting dust, so I said what the $@&!, and dumped in a 1/2 a bottle. Next day, with only just this small addition, the car ran fantastic and continued to do so. Surprising justs that small amount would make a huge difference. But it absolutely did.
So that really isnt a mixing story, per se, but more of a viscosity tuning story. ( as is actually promoted by MOTUL for their 300V series of products)
In the recent decade, I have found many rackety engines would enjoy the addition of Castrol Magnetec as a top off to make a noticeable difference in smoothness and quietness.
As far as true mixing goes, It was a hit or miss affair over the decades.
One Hit out of the park was running a Gallon of Rotella 10W30 T3 Triple protect mixed with a 1/2 qt of Formula Shell 5W30; this back in the API SM days in the decade immediately following Y2K all to keep the raucous Subaru boxer EJ253 happy.
Nothing Scientific here, just seat of the pants and other human senses, though I have posted a UOA of Valvoline and Magnatec mixed in a Subaru 2.0 in a moderate long drain scenario, and the UOA was phenomenal.
- Ken
