Synthetic Oil Question
 

I plan a switch to Synthetic Oil thi winter before it gets too cold.
Would Mobil 1 Synthetic 10W 30 be better than a switch to 10W40 standard oil? I'm running 15W14 right now. I plan to do a tranny fuild and filter change soon, any synthetic ATF fluids you guys recommend? additives?

I personally consider any rating less than 40 too thin for diesel applications. Especially older engines. Your area of Canada is much cooler in winter than mine but still I would observe the rule. The synthetic 10w 40 will have a lot less cold drag than normal oils. I still like the ideal of using the block heater when possible even when it is really not too cold to start but yet still pretty cold. The w after the first rating number I believe has some signifigance so checking for any synthetic oil displaying it might be worthwhile. You might want to check that out.

Mobil Delvac 1 or Mobil 1 Turbodiesel oils. Both are 5W40, synthetic and cost about $25/gallon (USA price).

EDIT: Links
http://www.mobil.com/USA-English/Lubes/PDS/GLXXENCVLMOMobil_Delvac_1_5W-40.asp
http://www.mobil1.com/USA-English/MotorOil/Oils/Mobil_1_Turbo_Diesel_Truck_5W-40.aspx

Same stuff, different bottle label.

On transmission with over 400,000Km's on it, should I change fluid and filter once a year? or with every coolant flush?

I'd do fluid and filter every 40,000Kilometers (25,000miles).

You can't use Mobil 1 10W30 because it's not a diesel rated oil and can't support the additional soot loading.

Check the container and ensure that the oil is rated either CH or CI. These oils will do the proper job for you.

If you want a decent synthetic oil at a reasonable price, consider Rotella-syn, 5W-40.

If cost is no object, consider Delvac-1. AFAIK, you won't find M-1 in 10W-40 with the CH or CI rating.

First time Mobil-1 user here
 

Coincidentally, I changed my oil and filter just yesterday, switching from Chevron Delo 400 10W-40 to Mobil Delvac-1 5W-40 (same oil as Mobil-1 Turbo Diesel Truck, only the packaging differs). The oil was purchased from a local commercial dealer for $124.54 (minimum purchase -- a case of four 1-gallon jugs) including sales tax and various state and federal anti-pollution fees. I'd like to find a less expensive source but at the moment, they are the only game in town. The on-line places are only a little less expensive after you add shipping.

The oil filter is my habitual "Turkish Fram," the CH2930. I have a stash from the sales that Pep Boys had earlier this year ($3.50 each including tax). So far, so good.

This is the first time I have ever used a synthetic oil; the purpose was to allow the engine to start more easily when I visit snow country this winter. If the engine seems to like the stuff and doesn't leak too much (it leaks none at all now) I'll stay with it in spite of the price. I may extend the change interval from my current 3000 miles to 4000 or 5000.

Jeremy

I get the M1 version from these guys for $7/quart with free shipping for $150 orders:

http://www.autobarn.net/mobil-1-diesel-truck.html

I have no problem with 5K oil changes with this oil, IMHO, 3K is overkill with a good synthetic. If you want to be sure, do an oil analysis.

I have yet to find any 10w30 or 10w40 weights that are diesel rated. Just get a 5w40 synthetic, mobil 1 15w50 is diesel rated as well dont know how well it would do in cold temps but i assume since its a group 4/5 synthetic it should be ok.

Mobil 1 0W-20 is also CF rated.

I don't have my manual in front of me, but I don't believe you want to use xW20 oil above about 40F ambient in a 61x engine.

I think there are a few members here that do use it.

I've heard that too, but IMHO it's just to thin for higher temperature use in older design engines. I drove about 700 miles today, I don't think I would want to do that with xW20, even in cool weather.

The better diesel rated oils are now CH and CI rated.

Know what the specific differences are?

This should explain everything: http://new.api.org/certifications/engineoil/categories/upload/ShelfCard_English.pdf