Which grade for the least consumption?

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The 10w20 is the answer. For the reasons Johnny likes a 5w20 he should REALLY like the 10w20 as it contains no VII and has a Noack of sub 4%. It’s the best choice if your climate supports it. As the Critic was asking questions about 3 of our oils I am answering the question with full knowledge of how they are formulated.
 
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Shell did a study years ago that demonstrated oil film thickness around the top of the rings was higher with a 20 grade than a 30 grade. I thought that was interesting. Oil consumption can be tricky due to so many variables, but generally speaking it seems the lower the VII spread/amount, Noack, the lower the oil consumption.
 
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Shell did a study years ago that demonstrated oil film thickness around the top of the rings was higher with a 20 grade than a 30 grade. I thought that was interesting. Oil consumption can be tricky due to so many variables, but generally speaking it seems the lower the VII spread/amount, Noack, the lower the oil consumption.
Coupled with AN and Ester to clean and keep it clean, will give you the best results.

David
 
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View attachment 117634

I will say that Subaru allows 5W30 or 5W40 as an alternate grades, temporarily. I can probably "explain" the use of 5W20 over 0W20 to the owner. Explaining 0W40 might be a bit more difficult.
They have to say "should be changed to 0w20 synthetic oil at the next oil change" the car and engine were certified on the thin oil.
I have run scoobies almost every winter for the last 15+ years, the difference from spec to the 0w40 is 0.2 mpg and never lost a cat.
The way some people go on about Euro oils smoking the cats is the most ridiculous argument ever. Euro cars should be littering the dealers and garages with bad cats even though they have to me the same standards and warranty.
If its a customer then run the 10w20.
 
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10w-20 to answer your question but considering winter temperatures, 5w-30.

Begining with quart every 2500-3000 was not bad enough to get concerned about.
i have been driving cars for almost 55 years. during 29 years of that time i did so literally all over the world in a foreign-based career. i have never had a car that consumed oil at a rate 1qt/3K miles, nor would i.
 

Shel_B

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$12/qt shipped if you buy 8 gals (two cases) at a time.

The cost of shipping varies depending on your location.
According to the site, it's $70.16 for a 6-quart case, but you can get a 15% discount using the BITOG code (I think it's BITOG15, but you need to verify that) plus shipping.

You can see the prices and order here:


At the site, scroll down for other variants. There are price differences for the variants.
 

Shel_B

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I will say that Subaru allows 5W30 or 5W40 as an alternate grades, temporarily. I can probably "explain" the use of 5W20 over 0W20 to the owner. Explaining 0W40 might be a bit more difficult.
Would you be able to explain using 10W-20 per Dave's suggestion? Have you decided what you will do?
 

FZ1

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10w-20 to answer your question but considering winter temperatures, 5w-30.

Begining with quart every 2500-3000 was not bad enough to get concerned about.
This^^^^^^^^^. 10-20 now, 5-20 winter, 5-30 late spring/summer.
 
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Oct 6, 2020
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You got the consumption down to 8 Oz on a FB25 just by running some HPL engine cleaner??? Impressive.

Use whatever grade you used that gave you that consumption. Any FB25 with some mileage, I'd say over 50k that uses 1/2 quart over 4k miles, I'd tell that owner to pick up a lottery ticket.

Although I never tried it, I have a friend with 2 of these engines. He said he had good luck with installing restrictors on the hoses that go from the vc to the intake. That's one thing you might want to experiment with if you have time.
 
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This I’ll add - a friend’s Forester with the phase 1 FB25, a 2012 drinks XOM oils. It’s doing OK on Pennzoil. I like Idemitsu oils in Subarus, they use MMA-based VIIs, the so-called “star” VIIs vs. the olefin polymers used by most blenders. This engine drinks very little on Idemitsu. I’m planning an OCI with Havoline ProDS 5W-30 soon.

His mom’s Ascent will be using M1 0W-30ESP at the next oil change. Why did Subaru call for 0W-20 on an engine known(on the Outback/Ascent forums) to shear oil, I dunno.
 
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