Auto-Rx cleaner / Marvel's Mystery Oil

[MonkeyWrench]

Curious as to your thoughts about two oil additives. One is an engine oil cleaner called Auto-Rx and the other one is an oil and fuel cleaner called Marvel's Mystery Oil.

[GeoffR]

Saab are very clear about this, Do not use additives.

[Digger]

From your profile your Saab is an 06 and should have always had 0-40 synthetic, if you have any reason at all to suspect sludge, drop the pan, clean by hand and make sure the pickup screen is clean.

Depending on where you've been getting your gas, fuel system cleaners may, or may not make any noticeable difference. In older vehicles I've used Marvel in the engine and the tank, I also use it in my air tools. For my Saab I use Lucas in the fuel system, no real noticeable difference in performance compared to other additives I've used over the years as they all help to keep the injectors clean. Shape of the container makes Lucas easier to squirt into the tank, but I think seafoam does a better job of preventing carbon buildup.

[GeoffR]

From your profile your Saab is an 06 and should have always had 0-40 synthetic, if you have any reason at all to suspect sludge, drop the pan, clean by hand and make sure the pickup screen is clean.

Completely agree but the 9-3 isn't known for sludge problems, that was the 9-5 and the problem was fixed post 2004. Sludge was caused, partly, by the use of semi-synthetic oils.

Depending on where you've been getting your gas, fuel system cleaners may, or may not make any noticeable difference. In older vehicles I've used Marvel in the engine and the tank, I also use it in my air tools. For my Saab I use Lucas in the fuel system, no real noticeable difference in performance compared to other additives I've used over the years as they all help to keep the injectors clean. Shape of the container makes Lucas easier to squirt into the tank, but I think seafoam does a better job of preventing carbon buildup.

Injector cleaner is a different matter and you have different products from the ones in the UK but they should be used as directed and only occasionally, modern fuels are much cleaner than older types and coking is much reduced.

[MonkeyWrench]

Great to hear your thoughts [emoji106]


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[Digger]

Completely agree but the 9-3 isn't known for sludge problems, that was the 9-5 and the problem was fixed post 2004. Sludge was caused, partly, by the use of semi-synthetic oils.


Injector cleaner is a different matter and you have different products from the ones in the UK but they should be used as directed and only occasionally, modern fuels are much cleaner than older types and coking is much reduced.

I will say it again:
If you have any reason at all to suspect sludge, drop the pan and make sure you have a clean screen. You never know what's been poured down the throat of a used car. Even if you're the original owner, if you don't change it yourself, or you didn't watch when they opened the jug, you don't know for sure that the Mobil 1 you paid for was semi or full synthetic. Sometimes the wrong stuff gets used and 10,000 miles on the wrong kind of oil can make a lot of sludge.

Depending on where you've been getting your gas, fuel system cleaners may, or may not make any noticeable difference. Unleaded gasoline is a perishable commodity and it gets traded as a commodity. There is a lot more to gasoline than octane and like fruits and vegetables, how long it takes to get to your plate makes a big difference in how good it is.

[RoccoH]

Again, as GeoffR already pointed out: black sludge is a significant issue with the B205 and B235 engines (and less with the B204 and B234 engines), but not with the B207 engines of the 9-3 NG.

ps Mobil 1 is always full synthetic...

[swisssaabist]

cleaners increase the mechanical wear of engines like tappets.

[GeoffR]

cleaners increase the mechanical wear of engines like tappets.

I'm not sure where you get that idea from. If a cleaner (flushing oil) is used correctly and then completely removed, by flushing with new oil, there is no reason why it should have any effect on engine wear. However many people simply drain the engine, fill it with flushing oil and then drain that and refill with normal oil. The correct method requires that the normal oil be replaced again before returning the engine to service.

Injector cleaner will be entirely burned by the combustion process and has no effect on engine wear.