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I finished my stash of big jug Mobil 1 15w-50 and I've been to the same Walmart that used to supply them and now find it that they don't carry it anymore. The other auto parts stores around don't carry it... and if they do, they only have a couple of the 1qt bottles. Anyone know where they can be bought? Anyone know of a good synthetic alternative to Mobil 1 15W-50?
 

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83 380SEC/85 500SEC/91 560SEC | 92 500SL | 92 190e 2.6 5-speed/92 190e 2.3 5-speed
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Amsoil makes a good synthetic oil, it even has the zinc our engines need (I think they call it XL). I used it on my coupe for a while and now will be using 10w-30 on the w140 for the winter. I haven't seen M1 15w-50 here either, that viscosity must not be popular on the east coast.
 

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'84 500 SEC Euro 040 black Lorinser 2005 sl500
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Hey Doc, the Mobil 1 15-50 jug search has been the topic of choice on the Harley forums since spring. Seems that the jug size was a Wally World exclusive and has been discontinued. What is on the shelves is all there will be in the jugs. You supposedly can still get the 1 qt bottles at O'Riely/Checker, but at about $8 a quart.
 

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1986 Euro 300SEL
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Amsoil makes a good synthetic oil, it even has the zinc our engines need (I think they call it XL). I used it on my coupe for a while and now will be using 10w-30 on the w140 for the winter. I haven't seen M1 15w-50 here either, that viscosity must not be popular on the east coast.

Same here. I use Amsoil 10/40 or 20/50, it has the "extra zinc" and has worked well for me for many years now. Order it online, comes right to my door. Any size you want, including quarts, gallons, 2.5 gallons, etc.
 

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Euro 1985 500SEL
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So what's the deal with the extra zinc guys? Why is this good and why do we want it? =)
 

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83 380SEC/85 500SEC/91 560SEC | 92 500SL | 92 190e 2.6 5-speed/92 190e 2.3 5-speed
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So what's the deal with the extra zinc guys? Why is this good and why do we want it? =)
Nowadays most oils have very little zinc, so the "extra" is what was normal when our engines were designed. It extends engine life and prevents premature on wear on crucial engine parts (Cams, rockers, etc.) There are a few additives you can use or try to find an oil that maintains safe zinc levels. Amsoil is a great synth that has a good amount of zinc. A few members here also like to go with diesel oil for many reasons, zinc levels being one of them.

Not trying to start an oil battle, its what I've used and tried.
 

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w126
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It's a beneficial lubricant for flat tappet engines. What I read differs from what others have said. The story I read was that the engineers determined that 800ppm(IIRC) of a zinc compound was the optimum or recommended level for use as an oil additive. Later on the level was increased in oils. It hadn't been determined that the higher level was needed from what I understood. Oil manufactures now are reducing the zinc level. Even at the reduced level they're still above 800ppm. Who really knows?

Edit: I don't remember for sure but I think detergents used in oils were a factor.
 

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1990 506SEC WHITE/GREY, 1990 560SEL WHITE/GREY, 2002 AMG E55
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I was told by the dealer Castrol GTX 20-50 is good for our cars. Does it have a
higher level of zinc ?
 

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MBZ '85 380SL, RR '77 Silver Shadow II, MBZ '98 E300TD, BMW '02 E46
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I was told by the dealer Castrol GTX 20-50 is good for our cars. Does it have a
higher level of zinc ?
Diesel oils are the ideal, they have ZDDP (zinc-phosphate), boron, acid neutralizers, soot and ash control far in excess of the gasoline engine additive packages. Additionally, marine rated diesel oils have corrosion inhibitors that will grow increasingly important for the finer examples of these cars as the years roll by.

The reduction in zinc phosphate came about as the result of the usual bean-counter cost benefit analysis. It was cheaper to change the oil spec and reduce the ZDDP additive that slightly reduced the useful life of the catalytic converter then to improve the catalytic converter. All engines burn a small amount of engine oil, less ZDDP and you get a few extra miles of use out of the catalyst. To make sure they got 100K average life out of the catalystics, they reduced the ZDDP some 40-50%.

Heavy duty diesel engines until recently didn't have catalysts and needed all the additive packages to assure long engine life (often in excess of 1 million miles). It's because of these engines automotive diesels and light trucks get the benefit of a rich additive package and gas motors can benefit (with a minor blip in catalyst life, nothing is "free.").

I have two diesel cars right now and two gas. They all get diesel oil, either Amsoil Heavy Duty Diesel oil or Mobile 1 Delvac diesel oil. All of these cars have catalytic converters and it doesn't worry me a bit about cat life, I've had to replace all of them at this point from the existing mileage on the cars when I bought them. The Amsoil has the additional marine rating (additional anti-corrosion protection package) and I'll probably have everything running on this from now on (used initially on my Rolls SS II gas motor after transitioning from Rotella T).

I'd advise at least trying a diesel oil for one or two of your full oil/filter change intervals. 15w-40 and 5w-50 full synthetic diesel oil covers all climates and provides every additive I care about and then some. Unfortunately you won't see the benefits of what doesn't happen, but it will add life to wear parts and pays dividends years from now when the motor doesn't need a full rebuilt to get back on the road.

-bh
 
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