mixing oils

[BEJ]

Can oils from different manufacturers and different type - semi synthetic, fully synthetic or non synthetic be mixed.
I am not certain which oil I have in my SLK230K at the moment, but I have got some Castrol Magnatec semi synthetic available for top up purposes if I need it but I'm not sure whether to use it or not.

 

[The _Don]

Best to drain and put in all new oil.

 

[Will]

Sounds a bit OTT.

For a top-up, any oil that meets the correct specs will be fine

 

[npuk]

Have you just got the car? Often stated in the service book or on the invoice of the service what oil is used. Generally if it is just to top up it will be fine as long as it is the right oil for your car.

 

[BEJ]

Just says Castrol 5 - 40

 

[ray_hennig]

Can oils from different manufacturers and different type - semi synthetic, fully synthetic or non synthetic be mixed.
I am not certain which oil I have in my SLK230K at the moment, but I have got some Castrol Magnatec semi synthetic available for top up purposes if I need it but I'm not sure whether to use it or not.

If it has the appropriate MB spec, I'd bung it in.

RayH

 

[flango]

Not good practice mixing fully synthetic and semi Syn or mineral oil, I wouldn't do it. If the OP is not sure what is in I would drop the lot and start again. £40 of oil Vs £100's of potential engine damage, it's a no brainer to me

 

[renault12ts]

Your car should have fully synthetic oil. On that basis, and assuming that's what's in it...do not mix with semi synth.

 

[flango]

Your car should have fully synthetic oil. On that basis, and assuming that's what's in it...do not mix with semi synth.

That depends on year doesn't it? Mine CLK is a 230k and runs semi syn, I would not dream of putting fully syn any where near it (but we'll not get into that )

 

[renault12ts]

That depends on year doesn't it? Mine CLK is a 230k and runs semi syn, I would not dream of putting fully syn any where near it (but we'll not get into that )

Ian, I defer to your greater knowledge on the car.

 

[flango]

Ian, I defer to your greater knowledge on the car.

I don't really have any greater knowledge I just know the early kompressor engines like mine run on semi syn and the later ones on fully syn and I am assuming the SLK is the same as the CLK in this respect

But I totally agree with you I would never mix the 2 oils, if you don't know whats in then time to change it for something you do know