old 300

I was wondering about the use of synthetic oils in the 5.9 engine. I am using Castrol RX 15w-40 now but was thinking about Canadian winters it might be better to use something different. My truck is a 2001 with only 27,000 miles on it. I do mostly short start and stop driving and short distances so I want the best.. The winter temps. here are on average 10-30 degrees F with the odd night going to 0F. Any help would be great.

PourinDiesel

Try a 0w40 or a 5w40 full synthetic.

TORQUE

I always have used Mobil 1 10w30 full synthetic for late fall thru to early spring with great results. Either 5w30(40), or 10w30(40)(diesel rated) will be good. 0w30(40) is a little thin for my liking( more of an arctic use) unless you don't park it in garage overnight, or can't plug it in during the day.

Anyone of these will make it start much easier, protect better, and warm up engine faster. Use a winter front, and don't excessively cold idle. I installed a manual toggle hi-idler to bump rpm's up to 1300(adjustable) or so when idling for short intervals, which keeps engine temps up to 190F or more. This will help burn off contaminants in crankcase, and keep valves from sticking.

Dr. Evil

1 suggestion:

ESSO XD-3 Extra 0W40 Synthetic. CHEAP (for a synthetic) from a ESSO bulk station.

VADSLRAM

I've been using Amsoil Synth diesel oil since I bought the truck (it had 7k miles when I switched).
I'm using the series 3000 5 w 30 and cold starts are a breeze. I've left it in the airport parking for a week of below zero weather hopped into it and she fired right up and only rattled and smoked for about 2 or three minutes.
The Amsoil blend has a high total base number that makes it good at keeping acid out of the crank case. Castrol's Tection Extra has a TBN of 10.1 Series 3000 is 12.2.
I've been using Amsoil products for 20+ yrs and I love em. They are more expensive initial cost, but extending the drain intervals offsets the costs and I "believe" that it is better for the engine. I've got no hard proof but that's a good thing never having to change bearings and all.
I do notice that all things equal my vehicles run cooler then dino oil ones. They say Synth moves heat better..
Any old timer MotoXers out there remember when BelRay first made synth 2 stroke oil? I switched as a goof and notice BIG improvements in power and crud buildup.