Winter in WY regularly hits -40, making for brutal morning starts. While switching to a syn is one option kind of worried about leaks. Running a dino how thin can I go in the winter? BTW 89 f250 460 with 87k.

 

Well if the engine is tight & isn't leaking now, switching to a synthetic shouldn't be a problem.

When you say -40 starts are brutal, it sorta suggests the vehicle isn't in a heated gararge & or doesn't have a block or battery heater, so do you at least have a block & battery heaters & is the vehicle at least in some kind of shelter?????

Their are now safe to use synthetic 0W-30 lubes that should meet your cold weather start & use needs, as at those temps, one would also need to think about cold restarts during the day!!!!

 

Truck is parked outside, no shelter, no heater. Would 5-20 dino be alright?

 

One question that I don't know the answer to: what would the owner's manual actually recommend in terms of oil weight for that kind of temp range?

It's been years since I've driven a vehicle of that vintage (except for my '91 BMW 318is, which I recall recommends 15W40 down to about zero F and up to infinity, and for constant temps below 32 F, I think, they say to use a 5W30). Think I used to use 10W30 or 40 in most everything domestic back in those days...but Mich winters rarely go below -10 F.

My gut is that a 5W30 dino or Motorcraft syn blend might be a good starting point for you if you're afraid of a syn at this point. If it doesn't use excessive oil, then using 5W20--like Motorcraft again--might be good in the winter. Or even mix 5W20 and 5W30 as a compromise....

And someone mentioned Rotella 5W40 syn and I think that might work out really well--especially if the engine sucks down some oil with 5W20-30 weights. My BMW has gotten a LOT of Rotella 15W40 dino in its life and it's as clean as a whistle inside the motor. I'd switch it to the 5W40 Rotella syn but it's got a gasket leak on the oil filter stand that I've gotta fix first.

George

 

Well not knowing if anything has been done to the engine over the years, or if it still has the OEM engine in it, it's hard to say what is ok to use.

I notice you have another thread on the same subject on this forum.

If you know or can get the engines history, have the owners manual, check this TSB out for the engine/cam & lifter type you now have in the engine, you should be able to make a wise choice on a winter lube.
5W-20 TSB 02-1-9***ENGINE - ENGINE OIL - RECOMMENDED APPLICATIONS FOR SAE 5W-20 AND SAE 5W-30 MOTOR OILS - GASOLINE AND FLEXIBLE FUEL VEHICLES ONLY

If the engine hasn't been messed with, (no high lift cam, or increased spring rate valves have been installed) the cam is stock, such that the valves are not heavily loaded & you have flat tappet lifters & stay with an oil that says it's backwards compatable with previous (S) grades, seems to me you'd likely be ok.

Now if the engine HAS been modified with a high lift cam & stronger valve spring rates & is a flat tappet type, with that increased camshaft loading, you'll have to be more careful about the lube you choose, to protect the camshaft.

Seeing as how it'll be sitting unprotected outside in temps down to -40F, anything you can do to help it start, sure will make YOU & IT happier this winter!!!!!

So I'd consider beginning to look for battery, block & maybe a dipstick heater too, along with a good synthetic cranksase lube, which you certainly could make good use of under these cold conditions, cause your battery is gonna need all the help you can give it, to be able to crank that big ole cold engine this winter!!!!!

More thoughts for pondering.

 

Truck has not been modified at all. I am the third owner and I know the original and previous owner. It has 87k, only things that have been changed are the oil, plugs, brakes, serp and a water pump. Still has original clutch.

 

Well if the engine hasn't been changed out for a newer model, hasn't been messed with internally & is stock, it isn't listed to use 5W-20 in the above 02-1-9 TSB & is likely still speced to use 5w-30 in the 99-8-16 TSB.

BUT, seeing as how it'll be sitting outside, unsheltered in down to -40F temps, you'll need a mighty good low pour point synthetic lube, in order to get that large displacement engine to turn over at those temps & no 5w-30 lubes have a pourpoint at -40F.

So maybe consider Chevron Delo Synthetic 0W-30, as it's pour point is -60F, so it should still flow at -40 without heating.
The Delo has plenty of Zinc & Phos for the cam, flat tappet lifters & main bearings.

BUT imo your sure gonna have to do something about the battery, because at those temps you'll not likely get more than one or two tries to crank that BIG puppy, unless you take the battery inside at night, or have a heater for it, or the block.

More thoughts for consideration.

 

Thanks for the replies.

 

I'd instal a block heater or at least a dipstick heater. The dipstick heater obviously goes in the dipstick tube, you plug it in and it keeps the oil in the pan warm. -40 is brutal, ought to have a heater of some sort. I'd go full synthetic.

 

Let us know what you do & how it turns out this winter.

 

Use only full synthetic. At -40 this is your best option by far.

 

With -40, I'd also say synthetic is the only way to go. A 0W-30 at that. And my favorite 0W-30 is Castrol Syntec. It's the only one made in Germany. I'm not a big fan of the rest of the Castrol Syntec line up, but the 0W-30 is excellent.

 

Also, at those brutal winter temperatures, I'd make sure I'd repeck my front wheel bearings with a good quality, synthetic grease.

At -40 those bearings will get mighty stiff. A synthetic grease will allow the bearings much better lubrication during the initial drive after a cold start, until the grease can warm up on it's on. I'd also lube the U-joints with a synthetic grease, and especially any and all grease fittings for the chassis.

Tie rods, ball joints, bushings, ect. don't neglect those parts.

Ed

 

I would add that full synthetic gear lubes are also a must at that temperature.

Jim

 

0w-30 and biggest battery you can fit in it. Block heater,battery heater also are good upgrades. I have a 97 F350 with the 460 and i run 0w-30 starting in December till at least march. We also get to -40 and colder. Plus add in windchill. Never had a problem with the 0w-30. Run mobil syn all the time. The clutch and tranny gets awfully stiff in that much cold. I have started it when it was -50 unplugged and it was not fun. So put in the heaters and big battery you will like it later.