i did an oil change today and instead of putting ordinary castrol 10W40 oil i used Mobil 1 synthetic oil. My mechanic recomended me to put 7 qrts in the 300D. I test drove the car and the oil pressure was up at the 45 bar at idle at the start. After 10 minutes of driving, the oil pressure was down between the 15 and 30 bar. Is this normal? should i be worried? i checked for leaks since they say synthetics are more slippery than conventional oils and tend to consume and leak more. There were no leaks at all. I'm an very worried about the consumption rate because during those 10 minutes of driving...the car smoked a little more than it did with regular oil............doesn't seem right


gladly appreciate the responses
allan

Just monitor your oil usage.. if increase, switch back. When the car first starts with cold oil, the pressure will be pegged. Once it gets warmer, it will be in the middle of the guage, say 1.5 BAR or about 23 PSI.

John

Does the pressure rise to 45 upon acceleration or remain btw. 15-30? Because the needle should be pegged above 1000 RPMs.

yeah it rises on acceleration pegged, but then it drops considerbly down close to the middle of 15-30 psi

I use Mobil 1 15-50 in my 85 300SD and I get about the same readings at idle on a warm engine. However, I do notice that when the oil has just been changed fresh from the bottle the psi will read about 5 psi less than it was before the oil was changed. This may be a good indicator as when to change oil, probably because dirty oil is harder to pump and creates a higher pressure reading. Has anyonelse had similar observations?

Get onto the Mobil 1 Delvac. This is a synthetic oil specifically formulated for diesel engines.

Oil in a diesel engine not only lubricates but carries away a lot of garbage. While the oil is residing in your engine it is collecting SOOT and other impurities not found in a gas engine burn. These impurities have to remain suspended in the oil so as to not become varnish on delicate internal components. This is even more true for the later models that have the EGR (more soot recirculated back into intake). The diesel formulated oil will keep the impurities suspended until drained. Oil designed for a gas engine won't suspend most of the gunk and will allow a diesel engine to build up gunk on the delicate gizmos on the inside of your engine.

You are better off burning a traditional oil formulated for diesel than a synthetic formulated for gas.

Allan, you don't mention what year your 300D is. Your oil pressure reads up to 45? Both of my diesels have the bar scale of 1,2,3. For a diesel, you should use a diesel rated oil. Now granted any full synthetic oil has a "C" rating, but I think anything-30 is probaly not what the owner's manual recommends. I don't have my manuals on hand, but I don't think 10W-30 is recommended except for extreme cold temps. If you're going to use synthetic, do like mccan said and use Delvac 1.

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The oil you put in is NOT RATED for a diesel engine!!!! If you want to use a Mobil synthetic the only one is Delvac 1. Get it out and get a diesel oil in the engine ASAP. Oils are designed for specific applications and you need to use one that is designed for your application.


Delvac 1 is the only synthetic oil made by Mobil rated for use in a diesel engine. If you use a gasoline spec oil you are going to have problems.

No cause for alarm.. you dont need to drain your oil ASAP.

In 4000 or so miles, switch to a diesel rated oil, weather it be synthetic or dino.

Where did you pick-up Mobil Delvac 1. I live in Sparta, NJ and work in Clifton NJ, and the only place that I can find that has it is a distributor in Carteret. Have you found a convenient local source.

JCD

Muybweno,

In an engine with that many miles I would have used Mobil I 15W50 unless it is very cold, less than 10 degrees. Some wear has to have occured in the engine and the higher viscosity oil will have a slightly harder getting past some of the wear areas like rings and valve stems and the engine will tend to burn less oil. I use Castro Syntec 5W50 in the 300SD I drive in the winter and Mobil I 15W50 in the 300SD summer car.

P E H

JCD,

I get it by the Gal. at PepBoys in Bridgewater. Just go to pepboys.com and do a location search. I've seen the Mobil 1 Delvac as well as Shell Rotella on the shelf at CarParts as well. Also, they carry the Power Service Diesel Fuel Treatment. HIGHLY RECOMMEND picking up some Power Service Diesel Fuel Additive (Gray or White Bottle) and pouring in half a bottle each fill up. Really makes a difference in the quality of burn you get from your fuel. The word is that most of the diesel fuel available right now is coming from Russia. Apparently there is not a great Cossack tradition in Quality Assurance.

Mercedes Diesel Meet tomorrow near Clinton, if your up for it.

I'll stop by the PepBoys in Parsippany on my way home. The last time I was in there 2 weeks ago, they didn't carry it.

I have to admit that I am a Redline addict, I get it at Manny, Moe's and Jack's, but I do use PowerService as well when it get's cold.

I was at the last NJ diesel meet, but I think the boss/wife is going to nix tomorrow's. I HOPE I'll see U there.

JCD

Hope to see you there.

Although Mobil 1 isn't as good a diesel motor oil as Delvac 1, it is rated for use in light-duty diesel engines. I would definitely put the diesel engine used in Mercedes-Benz automobiles in the light-duty category. I've been using Mobil 1 15W-50 in my Benz and have no intention of using anything else.

Sincerely,

Aaron