I am changing to 0W30 for this summer. I tow a lot during the hot summer months and the 20 weight oil is thinner than water when it get hot. The MDS system supposedly requires 5W20 to operate, but I have mine disabled so that's not a problem.

 

Think about this for a bit.

These engines, transmissions, are water cooled, as determined by the thermostat.

Engines in Texas, really don't operate under any different parameters than they do in Wisconsin.......

 

I beg to differ. Have you ever towed a heavy load on a 110 degree summer day? I have seen oil temps as high as 235 degrees while towing in the summer. Towing the same load in spring or fall the oil is easily 15-20 degrees cooler.

Remember that the radiator that that cools the water to cool the engine is cooled by air. 110 degree air passing through the radiator core is a lot different than 80 degree air.

 

You completely missed my point - a vehicle pulling a trailer in Wisconsin, at 100 degree heat, is no different than the same thing in Texas.

Yes, it does get to 110 in Wisconsin, but I'll bet you never see -40 in Texas...

 

I agree, we are over 80* for much of the year, ever seen 5w20 when it is 105*F outside and you change the oil on a truck that is being used. It drains out faster than water, no viscosity to it at all.

I run a 170*F thermostat, 1 ton Hemi Radiator, and a Flex-a-lite Efan with a variable speed control. Truck never runs hotter than 180*F, even taking a beating while towing.

 

"Remember that the radiator that that cools the water to cool the engine is cooled by air. 110 degree air passing through the radiator core is a lot different than 80 degree air."

Actually, not that different - you are only talking about a 30 degree differential, vs 195 operating degrees. And, the cooling system is designed for this (and more) differential.

 

and to add, i think you would have a hard time with warranty claim if you do have an engine malfunction and you were not running the 5/20 oil. just saying, why put yourself into that possibility if you are still in warranty (either lifetime or the 100K mile)

 

i would stick with 5w-20 as recommended by the manufacturer and just run a high quality synthetic oil

 

I have been running Mobil One 0w30 Synthetic in mind for over 20,000 miles. The MDS is turned off on my truck though.

 

I run 5W20 oil in mine. As it was mentioned above, I want to go by the rules since I have the 100,000 mile warranty and I plan on keeping this truck for a long time.

 

5W20 here as well I have ran that since I bought the truck and I have been through 3 hot a** summers, No problems. Now if your towing a lot then it may be different but just normal driving and even long road trips I wold just stick with the 5W20

 

So 5w20 is for the MDS.... I thought they were using it to squeeze mileage out of the engine.

 

No mds here and my RAM also takes 5w20

 

Texas,Georga, Key West, Maine its all the same. 5w20. I bet in heat of the summer theres not a degree of difference in oil temp from state to state. Texas is bigger.

 

There is a chart in the manual for the different tep ranges, check to see what they recommed for the temp ranges that you may incounter this summer.

 

If its a HEMI with MDS in a 1500 it calls for ONLY 5w20.

 

I'll bet the engineers who decided what oil to use considered climate variations. Just a guess though...

 

5w-20 here and wouldn't run any other weight. They are designed for it. If your worried about heat install a 180* T-Stat.