Pursuant to earlier posts regarding the perennial debates about oil,
today I put in a new oil filter and added Amsoil Flush, ran according
to instructions, then dropped oil, changed to a new filter again, and
replenished with Amsoil 15-40.
BTW, this is in a '79 non-turbo 300D with 200K.
Everything is running smoothly, albeit idle now a little high with
idle manual throttle closed, and I intend to extend my drain interval
from 2,500 to 5,000-6,000 miles, but am considering changing filters
at 2,500-3,000. Does anyone have any strong opinions on any of this?
Should I adjust my injector for the idle?
My opinion is to use rotella or the like because of the superior
particulate suspension. My sense (don't know for sure) is that a 79
diesel will make the amsoil just as dirty just as fast as dino oil.
Particulates in the oil are a source of early demise for diesels. My
opinion is dino oil changed every three thousand miles is a sufficient
and more economical choice.
The high idle could be a lot of things, e.g collapsed motor mounts
preventing the throttle linkage from returning all the way, rack
I tried synthetic, Amsoil and Mobile One in my 300 TDT when it had
about 350,000 miles on it. I just reinstalled the engine after having
it remanufactured. I am not sure if it was the synthetic oil, but my
engine, which had remained stable for a long time, went rapidly
downhill after I switched to synthetic.
I asked the owner at the place that remanufactured my engine, Metric
Motors in Canuga Park, CA if he would recommend synthetic oil. He
does not recommend synthetic. He feels that since the diesel engine
puts a lot of carbon into the oil the extended driving distance
between oil changes with synthetic is not a good idea.
I put synthetic oil into a couple of gas engine Toyotas that I drive
and I noticed an increase in fuel economy. I did not notice a boost
in fuel economy with my 300 TDT.
I was a bit confused by your message, in that if you had just had the
engine overhauled, then the engine would not have been "stable for a
long time" and therefore, the deterioration may have been due to some
factor other than the choice of oil, e.g., a bad overhaul, etc.
Ask the big rig truck drivers... they got the most mileage under their belt.
Synthetic is supposed to be far superior keeping carbon in suspension. New
Mercedes engine recommends 7500 miles per oil change... synthetic
as for 350,000 miles... come on! Getting 350,000 miles on an engine that you
are not original owner from beginning is already great.
Based on what I read synthetic oil *does not protect your engine any
better* it simply breaks down less over time and requires fewer
additives to maintain its viscosity. I can find no claims for improved
particulate suspension in any oils other than rotella or delvac.
Diesels generate much more soot and acidic combustion blow-by in the
crankcase. Turbochargers subject motor oils to high temperatures and
are more prone to form engine deposits. High milage engines generate
more blow-by as well. which is why changing oil in diesels more
frequently is better, it protects the bottom end of the motor.
So, according to the above you should still change your oil filter at
the frequency of the manufactures specification regardless of the type
of oil. As long as you are changing oil at the recomended intervals,
synthetic is not better (unless of course the manufacturer requires
synthetic, google the FSS law suit against mercedes for an example)
Anyway dino vs. synthetic often degrades into a religious debate and I
just don't have time for religious debates. I simply am saying what I
would do with regard to oil changes on a car of that vintage.
Particulates are to be controlled by the oil filter... There is zero way to
completely trap the particulate that it would clogged up the filter and
starve engine of oil.
By Mercedes design... those particulate still in suspension are not that
harmful as you would think until the point of high concentration.
How does one determine "success" with a particular brand of motor
oil? By the engine not failing when the stuff is in the crankcase?
But I understand what you mean about erring on the side of quality.
"Wit goes for the jugular, not the jocular." -- Florence King
On Oct 23, 6:56 am, email@example.com (Geoff Miller) wrote:
By "success" in this case, I mean that my engines get very high time
between overhauls, without breakdown or failure, thus attesting to the
efficacy of the products I use. I can say, conversely, that in my
younger, less enlightened days as a Pensoil devotee, I did not have
I am using Amsoil 5-50 in my 4.2 litre 420 sel, 1988. From what I
understand -BIG- deffernce. Synthetic is much more readily to lubricate,
especially in cold weather starts, which is hard on any motor. Synthetic
does not near "coagulate" like conventional, and can withstand heat better
as well. No comparison...
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.