Marvel Mystery Oil question

SkyVolvo · Post by **SkyVolvo** » 07 Jan 2011, 19:23

Hey folks,
I've got a '94 850 Turbo (220k, closer to 210k on engine) that seems to be burning oil - it looks like about a quart over the last 2000 miles, but sometimes it seems to smell like more. I thought I'd try a bottle of Marvel Mystery Oil and see what happened.

So here's my question, for any of you who might know better than I: since I just found out I'm about a quart low, can I just add a quart of MMO and run it for the next 1000 miles? Or should I go ahead and do it by the book, change it to fresh oil, and add the MMO then? I guess with clean oil it would be able to clean better - I don't know.

Also, any tips or suggestions for a car that seems to be burning some oil and producing a bit of a fuely/oily smell on startup? I'll pull the codes again soon, but last I checked, they were:

A1: 142 Oil Temp. Sensor Open Circuit (I've NEVER been able to find information on that!)
A2: 315 Evap (could be gas cap, could be plugged hose, I've heard)
232 fuel trim (should be fixed - one of the vacuum hoses had come loose)

Did the PCV in March, so that should be clear.

bobsnow100 · Post by **bobsnow100** » 10 Jan 2011, 07:29

I added 1 quart of marvel mystery oil once in a chevy van and it ended up spinning a crankshaft bearing. I would not do that ever again.

waynej · Post by **waynej** » 10 Jan 2011, 08:36

MMO is a good cleaner and cannot hurt your engine, bu it's not likely to stop the oil burning. Try changing your oil to Mobile 1 High Mileage.

aahmes57 · Post by **aahmes57** » 10 Jan 2011, 10:31

If you're smelling it, it may be leaking on something hot. My oil smell experience involved the replacement of the rear camshaft seal (exhaust side) that was leaking on something hot below the exhaust manifold. Replacing the PCV kit was only part of the problem. Now the oil cooant lines are leaking and I still have smoke coming out of the oil dipstick.

Post by **vjaneczko** » 10 Jan 2011, 19:43

Any kind of cleaning oil may freshen the gaskets, but also cause some of the gunk to loosen up and cause some leakage, but it should subside after a while. If it doesn't, you have have serious gasket problems.

AJ1G · Post by **AJ1G** » 10 Jan 2011, 19:56

What's the problem with 2000 miles per quart? I would be happy to get that on almost any car!

SkyVolvo · Post by **SkyVolvo** » 11 Jan 2011, 01:12

Actually, it may not even be a quart. I checked it more accurately, topped it off with half a quart, and called it a day. Since I have the MMO, though, I'll probably go ahead and run it at the next change (although...maybe I don't want to start fiddling with something that isn't giving me problems...). From what I've read, it's important not to let it get much past 3000 with the additive, right?

hrahn · Post by **hrahn** » 11 Jan 2011, 01:37

just add normal motor oil, it also contains cleaning additives. You can mix&match any oil, mineral and synthetic, 0W40 and 15W40 and so on.
Just remember, that if you add lower grade oil, you won't get the benefits of the rest of the higher grade stuff still in your system.

In the end, get some Mobil1 0W40 New Life and a fresh Volvo filter as well as some engine cleaner and do an oil change:
Put the car on stands, add the engine cleaner, let the car run in idle or slightly above for 10-15 minutes, then shut off the engine and drain the HOT oil out of it so that every piece of gunk comes with it. Remove the oil filter, put some oil on the seal of the new one and screw it in. Then re-seal the oil plug with a new copper o-ring, lower the car from the stands and top up slowly. You should nee between 5 and 6 litres (a bit of oil will always stay in the engine, sadly).
If the stuff that comes out is very nasty, top up with cheaper oil for cleaning purposes (cheap 10W40) and use some engine cleaner, drive it around with 1-2 days with that stuff and then flush and put in the Mobil1 with the fresh filter.
You will be amazed how smooth our engines can run when the goo is all out