Thickest oil grade you have run in winter, summer?

[DGXR]

Thickest... straight 40 weight in an old beater that burned and leaked oil, lost about 1 quart every 1000 miles.
Thinnest... 5w30 with MM oil. Never had a vehicle that spec'd anything thinner than 5w30.

 

[bluesmokertdi]

15w40 winter, 20w50 summer

 

[atikovi]

5W50 in a Pontiac G8 and I think I have it in an 07 Silverado 6.0.

 

[SR5]

Year round: Castrol GTX 20W50, Penrite HPR30 20W60 and Castrol Edge 10W60.

Right now I'm running a Penrite SAE30 monograde.

 

[JohnnyJohnson]

Adam its was 10-30 and in my climate, it made zero difference. On the warm wet side here in Washington I have seen several days in a row below zero. In fact as a young whippersnapper I started my 49 Chevy on 30 weight at 17 below. Dad had bet me it wouldn't start because it hadn't been started for two weeks. LOL

 

[earlyre]

growing up, we used 10w30 in everything.
when I got my 2000 Sonata in 2001, when I took it in for the first OC in my ownership, the guy (owner of the local VIOC Franchise) noted it was low, and said something along the lines of "these cars do that on that thin stuff" - the cap called for 5w30.
He Recommended I use 10w30, so I did.
It still burned a quart every 1000-1500mi. always Ran great Just Burned a little oil.
even switched it to Maxlife @ 75k mi, didn't affect the oil burn rate at all.

 

[Bjornviken]

10w40 and 5w-50

 

[BigShug681]

growing up, we used 10w30 in everything.
when I got my 2000 Sonata in 2001, when I took it in for the first OC in my ownership, the guy (owner of the local VIOC Franchise) noted it was low, and said something along the lines of "these cars do that on that thin stuff" - the cap called for 5w30.
He Recommended I use 10w30, so I did.
It still burned a quart every 1000-1500mi. always Ran great Just Burned a little oil.
even switched it to Maxlife @ 75k mi, didn't affect the oil burn rate at all.

That doesn’t even make sense because it’s the same grade oil

 

[Tdbo]

1985 Honda Accord. Bought it new.
Ran 20W50 Castrol GTX in it.
That's also what the dealer used in the service department.

 

[Inspecktor]

M1 0W-40 in everything except motorcycle, year round.

 

[captno4]

20w-50 in a 79 Trans Am with a 400 Pontiac in southern VA and west TX. Could not tell a difference.

 

[Vern_in_IL]

Straight up STP Blue Bottle oil treatment in a 5hp Briggs smoker!

 

[Zee09]

20w50 in a "78" Cordoba 360 lean burn with red Corinthian leather and red vinyl top

 

[Shel_B]

Back in 1970, I ran gear oil in my 1960 Rambler American wagon. Only did it for a few days until I could replace the engine.

Since then, the thickest I've run was an xW-40, although once, around 1980 sometime, I added a quart of 20W-50 to an old Oldsmobile convertible I was tooling around in. I was down some and the station I pulled into only had the 20W-50.

Oh, in 1965 I was heading home to NY from Philadelphia on the NJ Tpke, needed gas, and checked the oil. The ol' Pontiac straight-8 was down a couple of quarts so I added 2qts of straight 40wt re-refined oil for 25-cents a quart. With that stuff, even a VOA would be a UOA.

 

[earlyre]

That doesn’t even make sense because it’s the same grade oil

made sense to 21 yr old me that knew very little about that kind of stuff...I just did what the "mechanic" told me, and I ran a weight of oil I was used to using...

I didn't say it made sense to me now...

 

[Tifosi]

0W-40 year round in 2 vehicles and 0W-20 year round in 1.

 

[Bud]

20W-50 in my 71 MGB, engine and gearbox.

 

[BigShug681]

made sense to 21 yr old me that knew very little about that kind of stuff...I just did what the "mechanic" told me, and I ran a weight of oil I was used to using...

I didn't say it made sense to me now...

I didn’t say you did....

 

[K20FA5]

I ran regular old Castrol GTX 10w-40 year round in my old 97 BMW 318. That included winter trips to my folks up in KS. That was the first brand new car I ever bought. Cherry red! Also my first traffic ticket LOL!

 

[Accent Abuser]

5w50 and 15w40 in summer, 10w40 just above freezing in winter. Have both 15w50 and and 20w50 in my stash that will be getting used next spring and summer. Might even try 10w60 and have a UOA done with it in the summer if I'm feeling adventurous.