I just bought a 1977 300d, and i'm interested in maxing out mpg. I have read claims that using high quality synthetic oils like Red Line or Royal Purple can increase efficiency and miles per gallon. Can anyone confirm this? I think i will use these oils anyway, but i was wondering if anyone using such oils has noticed an increase. Thanks

 

Lower weight is the way to go. Anyone of the top synthetics in a 0W-30 or 0W-40 will be similar.

 

The highest quality you'll need is Mobil 1. Red Line and Royal Purple won't add anything and both apparently think it not worth their while to be Mercedes certified. Perhaps they can't meet the test--we just don't know.

 

When switching to synthetic oil, is it worth it to have a so-called engine flush performed to purge as much of the old regular oil as possible?

 

The MPG difference will on the order of 3mpg or less depending on your driving habits.

0W-anything is FAR too thin for an old engine and not diesel rated. 5W-40 is what should be used and its the most common synthetic thats diesel rated.

Avoid Rotella, its not an actual synthetic oil.

Mobil1 is the best around Amsoil gets their base oil from Mobil so you're just paying for a middleman and Royal Purple and other less commonly available brands have no measurable advantage to make it worth seeking them out.

Engine flushes will do far more damage than good, stripping the lubricating surface off a running engine is never a good thing. Do a short change. Instead of running the normal 8-10k miles for synthetic, do 3-5k instead.

 

Would 5w-30 be more appropriate for my colder climate in Chicago?

 

Only in a g@s engine.

 

There are so many myths about synthetic oil. When I taught auto mechanics, I told my kids synthetic oil is superior in all ways but one, and that is cost.

Rotella in the white bottle is dino oil. They do make it in a synthetic 5w-40. That is in a blue bottle.

I see no reason why you can't switch back and forth from dino to synthetic. I've done it in gas cars. As far as I can see the stories about leaks and such are unfounded.

 

That is not synthetic. A legal loophole allows it to be falsely marketed.
Group III oils are just normal dino oil that has been further refined. They still contain sulfur and natural contaminants that true synthetics never had.

 

diesel keep it on conventional oil at the manuals change interval. You won't pick up measurable mpg increase going to synthetic,your engine was not designed for synthetic and synthetics cleaning properties and small uniform chain molecule shape can lead to leaks in old gaskets and seals.Check tire pressure bump them up 5 lbs from factory setting,keep a clean air filter in it,just those 2 things will do more for mpg than opening yourself up to leaks on the old girl

 

There is no benefit to that.

Then that means your engine was not designed for ANY of the oils currently available.

That is false information. Synthetic will actually REDUCE oil leaks once it has had time to clean out the sludge left behind by dino oil's natural contaminators.

That can be dangerous in wet weather and hot days.

 

accounts.
Conventional dino oils are still available.
5lbs is fine for tires and if you look at speed ratings inside most gas caps that amount or around that amount is suggested and will not harm crap.Hot or not
synthetic will clean the varnish from gaskets that after 30 plus years can cause leaks.
As for the benefit of keeping the car on regular indicated service oil intervals ,that is only obvious.Or should be to a wisenheimer like you.
rolleyes:
Lastly at regular oil change intervals for his 30 plus year old hammer knocker he will not have a sludge issue.

 

You certainly were. Not in the specifications used when your engine was designed and produced. The oils produced in the 1980's are very different from whats on the shelf today. False. That is a myth perpetuated by people who have not used synthetic for any meaningful length of time. Once the sludge is clear, the seals are conditioned (softened) by the synthetic oil and seat to fit the new contours. Oil leaks are actually REDUCED with synthetic if it is allowed time to clean the engine. Both my engines marked their spots when used with dino oil, changing to synthetic eliminated ALL the oil leaks. They went from consuming/leaking 2qts every month to 2qts between oil changes (yearly/8k miles). Completely false. Factory OCIs are chosen to minimize maintenance costs yet ensure the vehicle will survive the warranty period. Obviously that means they are set much long to ensure maximum lifespan and efficiency. 5-8k miles is fine for synthetic, but far too long for dino oil. This is especially true for old high-mileage engines, they pump far more contaminants into the oil than when new. I don't expect a retired business exec playing mechanic, such as yourself, to understand how these things work. You can stick to your book, we'll use facts, real world knowledge and experience to keep ours going long after yours wear out. Incorrect again. ALL dino oils contain contaminants. These cannot be avoided or prevented except with true synthetic oil.

 

Here is a little Christmas reading on the subject :-

http://www.popularmechanics.com/auto...o/4213451.html

http://www.popularmechanics.com/auto...o/4232672.html

http://www.green-trust.org/2000/biofuel/lubrication.htm.

http://www.mobil.com/australia-engli..._v_mineral.asp

Merry Christmas.

 

The 30 plus year old engine was not designed nor the seals and gaskets designed for synthetic oil
No one suggested 8k mile oil change intervals with conventional oil.
Why does my1971MGB running conventional oil in the oe block engine never have a sludge issue? Because I change the oil on proper intervals. Why does my 300E never have a sludge issue.Why do my other Mg's never have a sludge issue? why do all the older Mercedes never........ Get the drift

Even the makers of synthetic oils state no leak issues in a good engine with good seals.You show me a 30 year old engine without worn old dry seals.
Synthetic won't remedy that condition.

If you need more proof.
From another site


If you've been driving around with mineral oil in your engine for years, don't switch to synthetic oil without preparation. Synthetic oils have been known to dislodge the baked-on deposits from mineral oils and leave them floating around your engine - not good. It's wise to use a flushing oil first.
If you do decide to change, only go up the scale. If you've been running around on synthetic, don't change down to a mineral-based oil - your engine might not be able to cope with the degradation in lubrication. Consequently, if you've been using mineral oil, try a semi or a full synthetic oil. By degradation, I'm speaking of the wear tolerances that an engine develops based on the oil that it's using. Thicker mineral oils mean thicker layers of oil coating the moving parts (by microns though). Switching to a thinner synthetic oil

(Like the op inquired about) can cause piston rings to leak and in some very rare cases, piston slap or crank vibration.
Gaskets and seals! With the makeup of synthetic oils being different from mineral oils, mineral-oil-soaked gaskets and seals have been known to leak when exposed to synthetic oils. Perhaps not that common an occurrence, but worth bearing in mind nevertheless.


So killing two birds with one stone.The op will not only not gain MPG he risks the above.
So we will have to agree to disagree.Okay

 

It was not designed for modern dino oil formulations, ULSD, WVO or BioDeisel either.

Correct, nobody did.

Because its a small, hard working, hot, g@s engine.

Look in my signature, you'll see two.

Incorrect.

From another business executive pretending to be a mechanic? No thanks.

Thats right, you need to replace the oil filter as well.

False. That is actually VERY good, and exactly what your oil filter was designed to prevent.

VERY false. Flushing agents are harmful to your engine!!! Also, thats a bit contradiction to what he said the the precious sentence isn't it? Especially considering flushing out deposits is exactly what synthetic oil does.

*Sigh*
False again.
Once you go synthetic, you should stick with it. However, returning to dino oil will cause no harm at all.

False again.

FALSE again.
There is that old myth again, perpetuated by people that don't actually use synthetic!

False AGAIN.
There WILL be a MPG increase, but not remotely enough to offset the higher initial cost of the synthetic oil.

Absolutely not. People like you spread false and harmful information, they need to be stopped.

 

mobil 1 makes the same recommendations for older engines.
Agree to disagree or not the op is the one who experiments at the cost of following your poor advice.
BTW thems real facts.And been playing Mechanic for decades before you were born and have yet to lose an engine due to oil related failure.So I doubt that any of your engine is going to out live mine.
The specs for modern dino oil as you call it are better now then they were back when the op engine was designed.They still don't have the properties that synthetics have that can lead to the problems stated.
Let the op choose.
I use synthetics in all my cars that call for it.
You use synthetic in all your car,okay.

 

Right, they suggest to use synthetic.

Corrected to reflect reality.

Apparently practice doesn't make perfect in your case.

So are synthetics, yet people like you are still scared poopless about myths they heard back in the 80's that were proven wrong even back then.
"I don't want to save money, get better economy, make my engine live longer or help the environment, my engine might leak a little bit for a few miles!"

Correct. It has natural contamination, sulfur and wax that cause sludge and carbon deposits, doesn't lubricate as well, doesn't last as long, doesn't suspend soot as well, is more harmful to the environment and is more expensive in long-term costs.

I bet you stick to the excessively long suggested OCI as well.

 

and a fleece filterOr longer if indicated by the fss.
Oil tested by the Lab 10k miles still above spec.
Gotta hand it to you though you are persistant.
From Mobil
"If an older engine is in good condition and does not have oil leaks, Mobil 1 provides the same advantages as when used in a new engine. ExxonMobil recommends taking measures to repair the leaks, then using Mobil 1. ExxonMobil also recommends following the automobile manufacturer's manual for the proper oil."
What does your manual call for? IS THE OP'S ENGINE IN GOOD CONDITION with no leaks?
Amsoil even has more caveats about using synthetics in older engines.
Glad you have had such success.M104 owners pull out their hair when switching to synthetics brings an early occurrence of the dreaded hg and timing cover leaks.
To each his own though

 

They are completely right.

Correction, the correct oil viscosity and API rating.

Thats because they are a low-budget middleman. They don't have a large R&D department like Mobil. In fact they simply buy Mobil's base oil, throw in their own additives and recruit outside salesman to peddle their products (and bring in even more franchise sellers).

Sounds an awful lot like a pyramid scheme doesn't it?

False information as well. Are you basing this "information" on forum posts?

When dealing with pretend mechanics like yourself, one must be or their false information and harmful advice will continue unchecked.

 

The way I see it & what I do is use a quality mineral oil in my 1980 Peugeot 504, a semi/ syn or synthetic technology oil in my 1996 Peugeot 405 diesel & a full syn top quality (Mobil 1 ESP 5w30 )in our 2008 220CDI.
In other words, I follow the vehicle makers lubrication recommendations. My previous 504 did 450,000 km on mineral oil without the head being removed & I am not grumbling about that . I sold it last year to an Egyptian who cut it up, placed it in a container with others for the spares market in the Middle East.So the motor is very probably still running well on mineral oil .

 

Geez, nothing gets people on a roll like motor oil. I think we all just need to realize that using the proper viscosity oil that is approved for diesel use and changing it before it wears out is the most important thing. I personally have never seen leaks caused by synthetics. I think that is a load of malarkey. I won't be running synthetic in my 300 D simply because of the cost. I don't want to spend the extra $ for synthetic's benefits in a 25 year old car when I could put that $ toward fixing other things. I use a good diesel oil and change it every 4k.

 

Thats why dino oils are still sold. People only consider the up-front cost and not the fact it actually saves money through longer oil life (OCI), improved fuel economy and reduced wear.

Average 12k miles/year.

1g Mobil Delvac 1300: $15. $30 per oil change.
Oil filter: $9
Add one gallon makeup oil per year: $15
Total for 3 oil changes per year: $132
Fuel used at 25mpg: 480g @ $2.80: $1,344

1g Mobil Delvac1: $35. $70 per oil change.
Oil filter $9
1g makeup: $35
Total for one oil change per year: $114
Fuel used at 25.3mpg: 474.3g: $1,328

Thats at least $34 per year saved, plus your time and work not lost on two extra oil changes. So by sticking with dino you're actually spending more money for a lesser quality oil that you have to take the time and effort to change more frequently.

Who knows, your engine might live for another 30 years instead of 29 years too! Only time can tell on things like that though.

 

If I were to drive my car tons and tons of miles, I would use synthetic and extend the change interval. The way I use my car (15 minute commute 5 times daily and the occasional trip into town) I'd rather change more often. I currently have synthetic in my Wife's Chevy because she is commuting over 100 miles daily and I will stretch the interval.

 

Thats a perfect application for synthetic.