Best oil for Diesel engines ?

[chilcutt]

How do Synthetic engine oils stack up against non-Synthetic ?

All feedback welcome.

[rocky raccoon]

Simply said, synthetic motor oils are far superior lubricants by any measure compared to petroleum oils. One of the best synthetic properties is resistance to heat. Diesels produce higher internal temperatures than gassers.

There is a persistent myth that using synthetic oil in an old engine will produce leaks. That may have been true 30 years ago but modern synthetics have no such effect. Basically, if your engine did not leak with petroleum oil, it will not leak with synthetic. I use synthetic in my 35yo 300CD (324k miles), my 2008 BluTek E320 (80k miles), my 97 Dodge (170k miles), outboard motor, weedwacker, everything.

My personal choice is AMSOIL but there are many fine synthetic oils out there. I use 15w-40 in the old Benz, 5w-30 in the newer one and 10w-30 in the Dodge.

I'm almost certain that others will post more scientific responses but that is mine and I'm sticking to it.

[t walgamuth]

The older diesel engines produce so much soot that it may be non productive to use synthetic.

[E150GT]

I use Rotella T6 5w-40 in my truck's gas engine...

[strelnik]

Originally Posted by E150GT

I use Rotella T6 5w-40 in my truck's gas engine...

According to what I have seen and heard from my indie mechanic who is MB trained from the old country and still has contacts, Mobil1 is approved (have to check the ACEA info) and it's also the oil I used in 0W40 for winter/summer in Michigan.

It's the only oil that will work in my 6.2 truck diesel to stay fluid in -4 F degree temps and it does not seem to leak in my 30 year old Hummer diesel.

In my Volvo 6324 engine I use dyno 5W30 because that's what is specifically recommended in the owner's manual.

Doesn't mean that others are not good, but I get good mileage and certainly no over heats or crusty stuff on the dipstick.

[chilcutt]

I believe this discussion should include oil filters as well.
Can anyone explain the differance between paper element and Fleece filters.
As well as which filter is best when used along with Synthetic oil.

[chilcutt]

Originally Posted by strelnik

According to what I have seen and heard from my indie mechanic who is MB trained from the old country and still has contacts, Mobil1 is approved (have to check the ACEA info) and it's also the oil I used in 0W40 for winter/summer in Michigan.

It's the only oil that will work in my 6.2 truck diesel to stay fluid in -4 F degree temps and it does not seem to leak in my 30 year old Hummer diesel.

In my Volvo 6324 engine I use dyno 5W30 because that's what is specifically recommended in the owner's manual.

Doesn't mean that others are not good, but I get good mileage and certainly no over heats or crusty stuff on the dipstick.

I always used Mobil 1 in the States...but the hot climate in Singapore, as well as the heavy traffic congestion means I do not need to consider a Cold Climate motor oil.
In my case, I am leaning towards Pennzoil Euro.

[chilcutt]

Originally Posted by rocky raccoon

Simply said, synthetic motor oils are far superior lubricants by any measure compared to petroleum oils. One of the best synthetic properties is resistance to heat. Diesels produce higher internal temperatures than gassers.

There is a persistent myth that using synthetic oil in an old engine will produce leaks. That may have been true 30 years ago but modern synthetics have no such effect. Basically, if your engine did not leak with petroleum oil, it will not leak with synthetic. I use synthetic in my 35yo 300CD (324k miles), my 2008 BluTek E320 (80k miles), my 97 Dodge (170k miles), outboard motor, weedwacker, everything.

My personal choice is AMSOIL but there are many fine synthetic oils out there. I use 15w-40 in the old Benz, 5w-30 in the newer one and 10w-30 in the Dodge.

I'm almost certain that others will post more scientific responses but that is mine and I'm sticking to it.

From what I understand, the leaks are a result of untimely oil changes. Over time the seals/rubber shrink or get hard if the engine has been abused.
Then, when switching to Synthetic oil , the oil is thinner, and may slip past the compression rings/seals..giving the impression Synthetic oils produce leaks..which like you said..just is not true.

[oldsinner111]

look up university study.Cummin's 15w40 was 1,and Rotella 5w40 syn. was 2.

[OM617YOTA]

That's like asking "what cheeseburger is the best?" There are minimal tech specs that must be met, and then a lot of preference and what works for individual engines/people in individual situations.

I run whatever name brand dino 15w-40 is on sale in my diesel during the summer, and whatever name brand 5w-40 synthetic is on sale during the winter. Both protect just fine, and I need to change them frequently due to soot loading regardless of dino vs synthetic. I run syn in the winter for better cold starts. Change at 3-5k miles.

I won't run Pennzoil or Quaker State in anything, ever. Not even my lawnmower, if my mower took oil. Formulas change and it's almost certainly a hold-back from a bygone era, but it used to be that you could smell when an engine had been run on either of those oils, the burnt paraffin smell would stay in your nose and on your hands all day. Horrid buildup on valve covers and such.

There have been a couple pretty gnarly oil filter threads. After cutting open a couple filters with a can opener, I will not run the normal Hengst/Mahle/Mann/etc oil filters. I understand that millions of engines have gone trillions of miles with these filters without oil related issues, but I pay a bit more for Hastings or Baldwin filters.

[iwrock]

No diesels here, but use synthetic in everything I own.

Ducati gets Motul 300V with OEM filter and the MB get an OEM fleece filter with Mobil1 0w-40. Ducati goes 6 months between oil changes, MB gets oil changed when FSS says it's time. No issues in either - oil looks fine when it comes out of both!

[chilcutt]

Originally Posted by iwrock

No diesels here, but use synthetic in everything I own.

Ducati gets Motul 300V with OEM filter and the MB get an OEM fleece filter with Mobil1 0w-40. Ducati goes 6 months between oil changes, MB gets oil changed when FSS says it's time. No issues in either - oil looks fine when it comes out of both!

How about the gearboxes..Synthetic as well ?

[cornemuse]

I have always used Pennzoil straight 30w in my cars, hasnt gotten to freezing here for 5-6 years.

-c-

[barry12345]

Originally Posted by cornemuse

I have always used Pennzoil straight 30w in my cars, hasnt gotten to freezing here for 5-6 years.

-c-

Your climate is very conductive to running whatever the manufacturer recommends for his engines viscosity wise.

My brother in law mentioned some time ago that oil pumps are now all aluminium. So he feels heavier than recommended viscosities should not be used with them.

Although I have not worked on really modern engines. If it is true it may be worth keeping it in mind.

[E150GT]

This may not be a diesel but I changed my oil today and this is what I had laying around. Hope my truck like the 20 grade...

[IMG]Image 7-10-16 at 12.39 AM by JOHN, on Flickr[/IMG]