should i use this oil in my 300tdt?its not listed in the owners manual.

The owners manual cannot be trusted, that oil did not exist when the manual was written.

If your engine isn't plagued with leaks at the moment, then 5w-50 synthetic should be fine, as long as its diesel rated. If it is plauged with leaks, you may want to fix them before switching to a lighter weight oil.

peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)

how do you tell for sure that the oil is diesel rated?

Oils carry an API donut indicating viscosity and rating. You'll see things like API SERVICE CF-I, or API SERVICE SJ.

The S designation stands for "S"park, C stands for "C"ompression. You need an oil that has the round seal and C something on it. I think the newest is CF-4 or CG-4.

Kevin

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'85 300SD

thats good info thanks.i was looking at castrol syntec 5w-50 but i notice it only has a SJ rating.its difficult to find a winter grade synthetic around here.looks like im gonna have to use 15w-40

Some places carry the Shell Rotella Synthetic, which is a 5W40 diesel rated oil at a reasonable price.

One of the 'best' oils for our diesels, especially in the frigid winter (which is also among the most expensive) is Mobil Delvac 1 5w-40, which can be had online at http://www.avlube.com which is a small business that handles special lubes. Its 80$ for 4 gallons. This spring I'll be blending it with Mobil Delvac Super 1300, which is a Diesel rated 15w40 dino oil for cost savings. Like I said, its expensive, but its also a great oil, and you can't go wrong with it for those hard winter starts.

Amsoil also sells a 5w40 fully synthetic, their series 3000, which is another great, but expensive oil that you might be able to find if you call a local Amsoil distributer.

Hope this helps! I'm not trying to start an 'oil thread' here, there are many oils that are good for our cars, just look for the C ratings, and change oil hot and often. I'm just pointing out a few popular 5W oils that are helpful for those of us in colder climates.

Peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)

thanks again for the good info.i saw the shell rotella but wasnt quite sure about it.it is definately priced a little cheaper than the other synthetics.the amsoil was on the shelf as well but premium priced.i may give the rotella a try as there is lots of positive buzz on this site