dodgediesel

I know this has been researched to the hills but I want to treat my motor right... I'm using Esso 15/40 diesel engine oil and it is time to change to synthetic. Can I go to a 0/40, 5/40 or should I stay with a 15/40. (Those are all synthetic oils I have to choose from). Are the 0/40 and 5/40 too thin. I'm worried that my new motor will leak from wherever it can. I live up north of the border and it does get pretty cold up here in the winter.(Right around the corner)

RJF

In a really cold climate 0-40 is fine. 5-40 should be fine nearly anywhere.

RustyJC

The lower SAE viscosity number is measured at 40 degC with the higher at 100 degC, the latter of which more closely approximates the viscosity at the oil's operating temperature. With conventional oil, achieving a higher viscosity index (VI - which produces the spread between the low and high numbers) requires heavy dosing with viscosity improvers, which are subject to shearing and deterioration over time. A synthetic base stock (ignoring the Group III, IV, V discussion) provides a naturally higher VI, so lesser doses of viscosity improvers are required to achieve the spread between 40 degC and 100 degC viscosities.

To shake it all down, the lower number really only comes into play at cold startup, where the lower viscosity provides better flow. At normal operating temperatures, a 40 weight oil is basically a 40 weight oil, although there is a range of acceptable viscosities within the SAE 40 classification.

Rusty

dodgediesel

Thanks Rusty, do you think my motor will develop leaks changing to a lighter synthetic oil are all synthetics the same??? (If that makes any sense.

RustyJC

One of the problems with the original Group IV (PAO, or polyalphaolefin) base stock synthetics was that they did not have the aromatic constituents present in "dino" base oil - these aromatics are what kept the seals and gaskets moist and pliable. With the early synthetics, the seals and gaskets would shrink and harden with leaks resulting.

Most of the Group IV synthetics now include a shot of a Group V constituent (an ester) to keep gaskets and seals healthy. Having said that, one still notes a few reports of leakage developing after switching to synthetic - I can't personally confirm or deny the validity of these reports.

I've never had a leakage problem on my vehicles that use synthetics - can't say about the Dodge since I still run Delo 400 in the Cummins.

Rusty

dodgediesel

Great info, thanks a bunch...

DeweyND

Hey, dodgediesel,

I switched my 01 to AMSOIL 15W-40 in July 05, at around 80,000 miles. No problems. And, I didn't have any trouble with it turning over/starting last winter either, but, I have the block htr plugged into a timer that comes on 3 or 4 hours before I normally need to start it. In my old 85 Ford 6.9, I also ran the AMSOIL 15W-40, and one night I forgot to plug it in. At -20F, motor spun over like it was +40F. That was the clincher for me to keep syn in it, till it started using a quart every 1500 miles. Then, went back to dino because it was cheaper.

Dewey

dodgediesel

Thanks bud...

ib516

I live in Sask (where it gets REALLY cold - no chinooks here ), and I use 0w40 Synthetic, it's made by Co-op and called D-Mo SL. Synthetic oils causing leaks is an old wives tale. Oh, BTW, calling a 0w40 oil "thin" is actually a mistake. Most people don't actually know what the viscosity numbers mean. I'll break it down for you.

0 - means that when cold, this oil will flow and exhibit properties of an SAE 0 weight oil - good start up protection.
W - good for "winter" use as defined by the API.
40 - Oil acts like a SAE 40 when up to operating temperature.

This is what is meant by the term "multigrade oil". It can act like 2 different oils, each having a benefit for the engine. Theorectically and practically, there would be no difference in performance in an SAE 40 oil and a SAE 0w40 oil when each is up to operating temperature. They would be equally as "thick" or "thin".

That concludes todays lesson...

For more on oil than you could ever want to know, surf on over to bobistheoilguy.com. Tons of oil info over there.

dodgediesel

Thanks.. I grew up south of Swift Current, so I know the winter you are talking about!!! Moved to Alberta and love the chinooks we always get here!!

Tate

I ran Rotella 0W40 synthetic in the truck last winter. Before the switch (never got below -5) , it would crank pretty slow. Afterwards, it would crank over like it was warm. The truck had 340k km on it, and no leaks. I'll probably dump the dino oil in the truck now when it gets cold and run the 0w40 again for winter time. If I find an oil analysis place in Calgary, I'd see if I could run it year round on the same oil change. $100 for just the oil makes for an expensive oil change.

ib516

$100 for the OIL???? I get mine at Co-op for $23.00 for 5L jug. 0w40 synthetic. Mind you, I always change it myself.

For oil analysis, I use Blackstone labs. They have a website, and will mail you a sample kit, then email the results. $20 USD on your cedit card.

Tate

It was $33.xx for a 4L jug at Canadian Junk. Only place I could find any synthetic in the city. You'd think Walmart would have some, but no go.