Is 20W40 okay to run this time of year in Colorado? I just bought my LBZ and that is what the dealer's oil change reminder sticker says it has in it. I see almost everyone else running 5W40...

I would run the 5w40. The 20W is too thick in cold weather, and your motor won't get as much lubrication on startup. Plus that is a little to much. I belive the recomended oil for the truck is 5W40 or 15w40 depending on where you live.

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I would never run such a thick oil in wintertime!
better go with 5W-40 or 10W-40.

Thanks guys! I just wanted to confirm it before I went and swapped it out!

I'm not even familiar with a 20w-40; is it a speciality HDEO for off-road diesels or something odd-ball like that? The common HDEO on-road oil viscosity is 15w-40, or 10w-30, or 5w-40. Where did a 20w-40 come from? What brand?

Doesn't really matter though; it's too thick for your purpose. Use either a 10w-30 HDEO for winter (then 15w-40 for summer), or just use a 5w-40 year round.

I'd be checking on a differnt dealer if that's the kind of service you're getting, unless he has a good explination.

There is a 20w40 I don't know what it would go in though. Maybe high heat areas.

20w50? maybe

the cold the oil the thicker it gets... and the thiner the rating you need

Be sure that you are running 5W-40 for diesel. I run Mobil 1 Delvac ESP 5W-40 and am pleased with it. http://www.mobil.com/USA-English/Lubes/PDS/GLXXENCVLMOMobil_Delvac_1_ESP_5W-40.asp But there are others available.

Is 20W40 okay to run this time of year in Colorado? I just bought my LBZ and that is what the dealer's oil change reminder sticker says it has in it. I see almost everyone else running 5W40...

Assuming that 20W/40 exists, it is too thick for temps much below freezing. GM says 15W/40 down to 0 deg F, but my Mercedes says only to 23 deg F. I am currently running 15W/40 in all my diesels, with our temps down in the single digits w/o running the block heater on the DMAX. My MB doesn't have CEL codes to throw...

20-40 is used in Yamalube (motorcycle oil). 25-40 is used in Mercruiser I/O's (boats). They probably misprinted it!

20-40 is used in Yamalube (motorcycle oil). 25-40 is used in Mercruiser I/O's (boats). They probably misprinted it!

Guess Mercury decided that the chances of someone using a boat when it was severly cold was minimal...

The tight viscosity range of a 20W/40 makes sense in a hard working, high revving air cooled engine for people worried about polymer shear.

20-40 is used in Yamalube (motorcycle oil). 25-40 is used in Mercruiser I/O's (boats). They probably misprinted it!

I was thinking the same thing.

Is 20W40 okay to run this time of year in Colorado? I just bought my LBZ and that is what the dealer's oil change reminder sticker says it has in it. I see almost everyone else running 5W40...

I think it is a typo. I hope so, otherwise you have to change it since it looks like you are in Colorado and they are putting a motorcycle oil.

Yeah, I thought it looked freaky, that's why I posted! Thanks for the help. I don't want to blow up my baby!

Regardless of where it came from, get it out of there.

Get either a 10w-30 HDEO or a 5w-40 HDEO for winter.

my motorcycle manufacturer recommends 20w40(100ci air cooled V-twin). It's around -8 right now wouldn't even think of starting it or using it in my truck.

15w40, 10w30, 5w40 are all acceptable weights.

Well, I got confirmation from my dealer that it was a misprint...nice catch guys. It is 15W40, so I'm gonna replace it ASAP!

If it is 15W40, it should be fine until the next interval, then you may want to use synthetic.