M1 0W-40/15W-50 mix, 12 mo/20k miles, '90 Saab 900

[Eiron]

Donald, I understand your concern. Unfortunately, this Caterpillar SOS lab is busy enough that they simply can't store tested UOA samples for weeks on end. My question to you (& others) is, would you be OK if they had said Si was 2 or 3? My next question would then be, what is the acceptable level of accuracy? I mean, we're talking about parts per million here. You'll never find a lab with "absolute" accuracy. I'm comfortable with the lab's accuracy, but I strongly encourage you & anyone else who's interested to give 'em a call & ask 'em any questions you have about the report.

Shannow, you be da man! I bow in reverence to your OCD calculative powers!

DmanWho, my feeling is that it's a combination of effective air and oil filtering. This OCI used an ACDelco oil filter, my current 20k mi OCI is using a PureOne. We'll see if there's any difference. My next OCI will sport a freshly-cleaned K&N & probably another ACDelco.

REDDOG, thanks! It's taken me a lot of studying, analyzing, & mental anguish to gradually push it this far. When I started using syn 110,000 miles ago, I wasn't even sure if my engine would still run after 10k mi w/o an oil change! With this oil in my current situation, I'm sure I could keep adding oil (& changing filters once a year) indefinitely.

-Greg

 

[BrianWC]

Eiron! Glad to see you're still at it with oil and SAABs!

M10W40 and 15W50, almost sounds like one of my mixes. But I usually go M1 15W50 and 10W30. I like the 0W40 too much to mix it.

 

[Eiron]

Hey Brian! Yeah, still at it. Can't get that oily monkey off my back just yet....

If I didn't have the 9³'s turbo I'd use 0W-40 in everything. Once you throw that into the mix, I'd prefer to use 5W-40 "TDT" in all our Saabs.

About two yrs ago Target had a clearance sale on non-API M1 15W-50 (post Katrina oil?) at around $1/qt, so I bought all I could find. That was about 35 qts. Mixing it with 0W-40 gives me something approximating 5W-40's properties at about half the cost. And at 1yr/20k mi OCI on my C900, I'm not going thru it all that quickly.

Mixing it with 10W-30 would give me something approximating 15W-40's properties, which is great for Shreveport but just a tad thicker than what I like for frequent sub-freezing (& occasional sub-zero) winter cold starts.

 

[Doug Hillary]

Hi,
Eiron - When mixing M1 products the 0w-40 and TDT 5w-40 versions makes sense as the formulations have many simularities

Other M1 products can be mixed too of course but the two mentioned above are different animals and don't benefit "at all" from mixing with the other M1 variants

 

[Eiron]

Hi Doug!
Originally Posted By: Doug Hillary
When mixing M1 products the 0w-40 and TDT 5w-40 versions makes sense as the formulations have many simularities
Do you mean mixing these two together?


Originally Posted By: Doug Hillary
Other M1 products can be mixed too of course but the two mentioned above are different animals and don't benefit "at all" from mixing with the other M1 variants
My goal with blending in 0W-40 is to be comfortable using the 15W-50 for CO winter starts but keep as much of the 40wt-50wt film properties as possible (since my UOAs show better results in this engine with 40wt-50wts). I also thought about mixing the 15W-50 with 0W-30, but I prefer the ACEA A3/B3/B4 rating that 0W-40 carries & 0W-30 lacks.

I forgot to mention that the clearanced 15W-50 is the EP version, so it contains similar additive chemistry to both the 0w-40 & 5W-40 formulas.