Tried 20w-50

[Johnny2Bad]

Originally Posted By: Stelth
I have a work van that is pretty old and beat up. It's a 2001 GMC Savana 1/2 ton, and I have no idea how many miles are on it. When I got it the odometer read a little over 120,000, but then it stopped working.
[snip] ...

For my end-of-summer OC, I put Quaker State 20w-50 in it. I figured that being thicker and having a super-low NOACK number, maybe consumption would be less. Nope. Mileage dropped a little, but not a lot. Oil pressure was about 5 psi higher when warm, 60 vs. 55 on the factory gauge at highway speeds. So when it was a quart low, I added a quart of Mobil 1 0w30 I had laying around to thin it out a little. For the next quart, I added 5w30 Pennzoil. I didn't see any point in continuing to use 20w-50.

Now winter is here, and it will soon be dropping into the 40's and 50's at night, so this time, I used Mobil 1 10w30 HM.


I'd have to look it up, but 10W~xx is good to go somewhere between maybe 10F and 32F (and above). By "good to go" I mean it meets 10 wt at those temps and must meet 20 wt at moderate temps (105F).

It transitions from 10 to 20 probably right at the cold temps you're experiencing (although this does vary with different oils; the W spec says nothing about what happens between the rated cold temp and the mandatory 105 degree F viscosity), so any multigrade may well be equivalent to 20 wt (or whatever the big number is) at 60F anyway.

 

[Johnny2Bad]

Sorry above should read "30 wt" where you see "20 wt" and at:
" …
By "good to go" I mean it meets 10 wt at those temps and must meet 20 wt at moderate temps (105F).
…"

should read [whatever the big # is] instead of "20 wt"

It's a myth that, say, a 0W-xx oil is any thinner than any other W-rated viscosity at room temps. It can be anything. We normally view the oil at the ambient temperature but no oil spends more than a few seconds at that temp in the motor, so we rarely observe it at it's actual operating temp in any case. But SAE / API demands it is at the [big number] viscosity at 105F.

You cannot "cherry pick" the viscosity; if it's 0W-40 it meets grade of 40 at both 105F and 212F, period, full stop.

 

[Lex94]

Living that far north in winter is a form of self-abuse...You all know that, right?

I get uncontrollable twitches when I even see a snow flake now.

 

[gfh77665]

Originally Posted By: 901Memphis
Put some sae 30 or 20w50 in a Dixie cup and put it in your freezer and then observe it's visual thickness and tell me if you want that kind of molasses in your engine.


I bump start my truck with this 30 w. "molasses". What I mean is as soon as the key bumps to the on position, the engine starts before I can even release the key. That 30 wt "molasses" must be good stuff!