Synthetic engine oil merely reprocessed petro oil? - PeachParts Mercedes-Benz Forum

Paul Divin · #1 04-05-2008, 12:50 AM

I have a 1984 MBZ 300D Turbo. A mechanic I went to today told me that the synthetic oil I can buy is not as good as the synth oil he gets. He said the stuff I can buy is merely reprocessed petroleum oil. That sounds like pure BS to me, but I need backup.

Also, for that 1984 MBZ 300D living in San Francisco, what synthetic oil should I use? Temps range between 30 to 85F. Right now the coldest nights are about 45F.

Thank you,
Paul

bgkast · #2 04-05-2008, 01:09 AM

Oils such as Mobile 1 and AMSOIL are true synthetic oils and are chemicly created from "scratch" not processed dino oil. Others such as Castrol Syntec are hydroisomerized (processed) petroleum oil.

DeliveryValve · #3 04-05-2008, 01:46 AM

Quote:

Originally Posted by bgkast

Oils such as Mobile 1 and AMSOIL are true synthetic oils and are chemicly created from "scratch" not processed dino oil. Others such as Castrol Syntec are hydroisomerized (processed) petroleum oil.

Also known as HydroCracked Group III base stock.

Mobile 1 and Amsoil have polyalphaolefins (PAO) base stock.

PaulH · #4 04-05-2008, 01:50 AM

AHHH Another oil thread! I love it!

pawoSD · #5 04-05-2008, 01:50 AM

My engine must make a lot of soot, because after running 5k on mobil 1 turbo diesel truck, it was what I would consider "too thick" when I was draining it. So, I switched to Rotella Synthetic and a 4k change....I'm thinking the 20% more often filter/full change on a slightly "lesser" (perhaps not even true) oil is better for the engine than extra miles on a "better" oil. Saves me a little bit of $$ too....and the engine likes it just fine....in fact I think it likes the rotella better than mobil. *flame suit on*

Bio300TDTdriver · #6 04-05-2008, 10:15 AM

Quote:

Originally Posted by pawoSD

My engine must make a lot of soot, because after running 5k on mobil 1 turbo diesel truck, it was what I would consider "too thick" when I was draining it. So, I switched to Rotella Synthetic and a 4k change....I'm thinking the 20% more often filter/full change on a slightly "lesser" (perhaps not even true) oil is better for the engine than extra miles on a "better" oil. Saves me a little bit of $$ too....and the engine likes it just fine....in fact I think it likes the rotella better than mobil. *flame suit on*

Why don't you get an oil analysis after the same mileage on both oils? Wouldn't that give you a little more information? Of course maybe you are an engine whisperer and you know exactly what your engine likes.

pawoSD · #7 04-06-2008, 01:25 PM

Quote:

Originally Posted by Bio300TDTdriver

Why don't you get an oil analysis after the same mileage on both oils? Wouldn't that give you a little more information? Of course maybe you are an engine whisperer and you know exactly what your engine likes.

Someday when I have more money I may do that, but as a college student, I can't afford to blow the $25 it costs to have the oil analysis done...that money is better spent on the car itself.

btw, I am an engine whisperer....I understand them and they understand me

Brian Carlton · #8 04-05-2008, 10:17 AM

Quote:

Originally Posted by pawoSD

My engine must make a lot of soot, because after running 5k on mobil 1 turbo diesel truck, it was what I would consider "too thick" when I was draining it. So, I switched to Rotella Synthetic and a 4k change....I'm thinking the 20% more often filter/full change on a slightly "lesser" (perhaps not even true) oil is better for the engine than extra miles on a "better" oil. Saves me a little bit of $$ too....and the engine likes it just fine....in fact I think it likes the rotella better than mobil. *flame suit on*

Yep, I agree. OCI at 5K doesn't warrant the expense of Mobil 1, except in extraordinary situations. Hell, the OC already costs $44 if you use Rotella Syn..........don't need to spend any more..........

And, it most definitely thickens if you push the OCI to 6K.

Bio300TDTdriver · #9 04-05-2008, 10:26 AM

Quote:

Originally Posted by Brian Carlton

Yep, I agree. OCI at 5K doesn't warrant the expense of Mobil 1, except in extraordinary situations. Hell, the OC already costs $44 if you use Rotella Syn..........don't need to spend any more..........

And, it most definitely thickens if you push the OCI to 6K.

Brian,

What are you using in the SDLs? What are your change intervals. I have about 5k on the Mobil 1 in my wagon. I was going to do an analysis at 6k, but you guys have me thinking about doing it sooner now.

On an unrelated issue (at least to this thread) what should I torque my new gasket to on the EGR plate?

Thanks,

Chris

pawoSD · #10 04-06-2008, 01:29 PM

Quote:

Originally Posted by Brian Carlton

Yep, I agree. OCI at 5K doesn't warrant the expense of Mobil 1, except in extraordinary situations. Hell, the OC already costs $44 if you use Rotella Syn..........don't need to spend any more..........

And, it most definitely thickens if you push the OCI to 6K.

Exactly, I figure a 4k change is way better.

I drained the last of our M1 oil out of the '83SD yesterday, it had 4,900 on the oil and it wasn't as thick as when I drained mine at the same miles....maybe my engine makes more soot. Either way, its also on Rotella Syn + 4k change now. So now all our cars are on the same oil. If we buy the 240d we've been looking at....that one will be changed over to it as well.

#11 04-05-2008, 05:09 AM

Quote:

Oils such as Mobile 1 and AMSOIL are true synthetic oils and are chemicly created from "scratch" not processed dino oil. Others such as Castrol Syntec are hydroisomerized (processed) petroleum oil.

Quote:

Originally Posted by DeliveryValve

Also known as HydroCracked Group III base stock.

Rotella's "synthetic" is Group III as well.

BoomInTheTrunk · #12 04-05-2008, 01:11 AM

while most synthetic is not 100% percent but rather a mixture of dino and synthetic what he is telling you is pure bs. If you buy mobile 1 not mobile clean 5000 or 7500 but the original mobile one that is a pure synthetic. that mechanic just wants your money dont listen to him, and dont take your car back to him. If he is trying to hustle you out of money on oil I cant imagine what he might do.

sixto · #13 04-05-2008, 01:29 AM

Quote:

Originally Posted by Paul Divin

A mechanic I went to today told me that the synthetic oil I can buy is not as good as the synth oil he gets.

We can't dispute his statement if we don't know what synthetic oil he gets. What sort of warranty does he offer with this 'better' synthetic oil?

Sixto
87 300D

imagesinthewind · #14 04-05-2008, 02:10 AM

my cars seem to like the synth Rotella too.
I switched the FL car to synth Rotella and no more leaking.

cphilip · #15 04-05-2008, 09:36 AM

Yes, some time back Mobil oil sued one of the other makers (I cannot recall which one) over this definition and use of the term synthetic and lost the lawsuit. So Hydrocracked petroleum bases can still be called Synthetic. They "almost" are. Problem is where they are derived from. Mineral oils can be refined from Petroleum. Just like Diesel can be extracted from Vegetable oils. There are slight differences but they are slight... and only a court decides if they are different enough to call the same it seems. Sort of like "fresh fish" at the market.

I am told the Mobil is the only company that makes the real base (PAO) and sells the base to Amsoil, Redline and any other manufacturer who wishes to buy it. Then these companies blend in their additives packages.