Thinnest possible oil you can put in a car?

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2,587
Location
Caldwell Idaho
You will never be able to measure the difference in mpgs if at all measurable by going to the thinnest oil. What oil does the manufacture recommend?
 
Messages
2,291
Location
WA
These engines are known to be pretty bulletproof , i used to own one and did a lot of 120mph prolonged highway runs where oil temps would reach 285f 140c, that was also on 5w40.

he should stay away from 20 if he drives anything like you!

also fuel savings will pay for a cup of coffee or maybe half a cup. :unsure:
 

SR5

Messages
5,932
Location
Down Under
I'd try a Ford WSS-M2C913D oil. It will be filly synthetic with a minium ZDDP of 1000ppm. Should be around 2.9 HTHS too
Yeah I can see your logic, if you did decide to go thin, a Ford 913D oil is a very thin 5W30 A5/B5 synthetic oil, but with extra ZDDP (~ 1000 ppm Zn) to combat the extra wear.

OP, don’t forget the old racing trick, and remove the spare tire and jack from the boot. If he gets a flat, tell him to use his phone and auto club membership. In fact strip the car back as much as you can get away with, while still staying safe and legal: air-con, radio, noise proofing, maybe the rear seat. Moving all those kilograms from a stationary start to up to highway speed takes energy and fuel.
 
Messages
1,473
Location
Indiana
Based on the race engine builder rule of thumb, any vis that gives you 10 psi (70kPa) oil pressure per 1000 revs will be fine for durability. So if 0W16 gives you 7-8 psi oil pressure at idle and 20 psi at 2000 revs on your hot days, should be fine.
 
Messages
7,518
Location
North America
Changing all the driveline fluids to synthetics will squeeze a little more efficiency.

As mentioned, inflating tires to maximum, slowing down and reducing weight will be MUCH more effective than anything else.
 
Messages
3,679
Location
Northern Ontario, Canada
Drive no faster than 80 kph / 50 mph, drive as if there is an egg under the accelerator pedal, don't use the brakes, proper tire inflation +10%, time the traffic lights.
Or take public transit.
These are the most effective ways to improve fuel economy.
 

OVERKILL

$100 Site Donor 2021
Messages
46,079
Location
Ontario, Canada
Based on the race engine builder rule of thumb, any vis that gives you 10 psi (70kPa) oil pressure per 1000 revs will be fine for durability. So if 0W16 gives you 7-8 psi oil pressure at idle and 20 psi at 2000 revs on your hot days, should be fine.

I believe that old "rule of thumb" was specifically geared toward the SBC and was just a general guideline, I would certainly not be using it as a validation mechanism for deviating significantly from spec. Honda went with wider bearings and journals for example when they started going thinner, and this was discussed on here at some length a while back as the Japanese OEM's were the first to really chase the ultra-thin oil thing.

I would never want the following exchange to play-out as a result of advice received here:

Bob: Gee Fred, how'd you toss that rod through the side of the block?
Fred: Well you know Bob, I was on this message board and I was told as long as 0w-16 gave me 10psi per 1,000RPM, I'd be fine, so I put it in and I had 10psi at 1,000RPM so off I went. Engine started knocking after I ran it hard up an on-ramp and then we had a big 'ol cloud of smoke and here we are!
Bob: Doesn't your engine spec like 5w-40?
Fred: Yes, but these boys were really convincing, they really seemed know their stuff!
Bob: Are they going to be paying to fix this?

*crickets*
 
Messages
4,709
I believe that old "rule of thumb" was specifically geared toward the SBC and was just a general guideline, I would certainly not be using it as a validation mechanism for deviating significantly from spec. Honda went with wider bearings and journals for example when they started going thinner, and this was discussed on here at some length a while back as the Japanese OEM's were the first to really chase the ultra-thin oil thing.

I would never want the following exchange to play-out as a result of advice received here:

Bob: Gee Fred, how'd you toss that rod through the side of the block?
Fred: Well you know Bob, I was on this message board and I was told as long as 0w-16 gave me 10psi per 1,000RPM, I'd be fine, so I put it in and I had 10psi at 1,000RPM so off I went. Engine started knocking after I ran it hard up an on-ramp and then we had a big 'ol cloud of smoke and here we are!
Bob: Doesn't your engine spec like 5w-40?
Fred: Yes, but these boys were really convincing, they really seemed know their stuff!
Bob: Are they going to be paying to fix this?

*crickets*

Why do I feel like I've done that a few times.
 
Messages
1,473
Location
Indiana
Changing all the driveline fluids to synthetics will squeeze a little more efficiency.

Our transmission spin tests at Allison indicated that synthetic and petroleum based fluids of the same viscosity showed no difference. Any advantage of "synthetic" was due to lower viscosity if the synthetic was in fact lower.
 
Messages
4,709
Bob: Gee Fred, how'd you toss that rod through the side of the block?
Fred: Well you know Bob, I was on this message board and I was told as long as 0w-16 gave me 10psi per 1,000RPM, I'd be fine, so I put it in and I had 10psi at 1,000RPM so off I went. Engine started knocking after I ran it hard up an on-ramp and then we had a big 'ol cloud of smoke and here we are!
Bob: Doesn't your engine spec like 5w-40?
Fred: Yes, but these boys were really convincing, they really seemed know their stuff!
Bob: Are they going to be paying to fix this?

I believe that old "rule of thumb" was specifically geared toward the SBC and was just a general guideline, I would certainly not be using it as a validation mechanism for deviating significantly from spec. Honda went with wider bearings and journals for example when they started going thinner, and this was discussed on here at some length a while back as the Japanese OEM's were the first to really chase the ultra-thin oil thing.

I would never want the following exchange to play-out as a result of advice received here:

Bob: Gee Fred, how'd you toss that rod through the side of the block?
Fred: Well you know Bob, I was on this message board and I was told as long as 0w-16 gave me 10psi per 1,000RPM, I'd be fine, so I put it in and I had 10psi at 1,000RPM so off I went. Engine started knocking after I ran it hard up an on-ramp and then we had a big 'ol cloud of smoke and here we are!
Bob: Doesn't your engine spec like 5w-40?
Fred: Yes, but these boys were really convincing, they really seemed know their stuff!
Bob: Are they going to be paying to fix this?

*crickets*
Your post now lives in my signature. That was funny.
 
Messages
1,473
Location
Indiana
If it ran good... no, I shouldn't do that. LOL
I believe that old "rule of thumb" was specifically geared toward the SBC and was just a general guideline,
I learned it in the 60s from an engine builder in Cleveland who did flathead Fords for stock cars. So it goes back many decades. And with oil formulas and metallurgy so much better now, I have to think it's still a good number.
 
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