Mixing Oils
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Joined: Jan 2001
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From: I sell sea shells by the sea shore
Mixing Oils
Question from a friend:
Are there any reasons why (aeroshell) 15W50 Semi synthetic oil should NOT be used to top up an engine (Continenal C90) running on "straight" mineral 100 oil?
Mate says this is okay because teh aeroshell is "semi" synthetic. I'm not convinced.
Don't know the answer myself as I've always stuck to W80/100.
Over to you, clever people.
Rgds BEX
Are there any reasons why (aeroshell) 15W50 Semi synthetic oil should NOT be used to top up an engine (Continenal C90) running on "straight" mineral 100 oil?
Mate says this is okay because teh aeroshell is "semi" synthetic. I'm not convinced.
Don't know the answer myself as I've always stuck to W80/100.
Over to you, clever people.
Rgds BEX
Joined: Sep 2003
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From: South Norfolk, England
The short answer is he's right, but the long answer is DON'T!
Theoretically you can top up mineral oil with synthetic, but there are problems associated with doing so. It's far better to stick to one oil type. If you decide to change, do it at an oil change and stick to the new oil from then on. Basically, mineral oils will soak into old gaskets and also sludge deposits may build up here and there. When you add a new sythetic oil it may act like a detergent and dislodge all the crap that's built up, and that's not a good thing! ... well at least it isn't when you don't want it too.
I'm not a great fan of straight 80 or 100 (for reasons you will know
) and prefer multigrades. I've not had much experience with synthetic oils, as I've always found mineral oils to do the job very well! 
However, I expect they do the job just as well if not better ... but I certainly would not mix them.
SS
Theoretically you can top up mineral oil with synthetic, but there are problems associated with doing so. It's far better to stick to one oil type. If you decide to change, do it at an oil change and stick to the new oil from then on. Basically, mineral oils will soak into old gaskets and also sludge deposits may build up here and there. When you add a new sythetic oil it may act like a detergent and dislodge all the crap that's built up, and that's not a good thing! ... well at least it isn't when you don't want it too.
I'm not a great fan of straight 80 or 100 (for reasons you will know
) and prefer multigrades. I've not had much experience with synthetic oils, as I've always found mineral oils to do the job very well! However, I expect they do the job just as well if not better ... but I certainly would not mix them.SS
Better red than ...
Joined: Aug 2004
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From: Appleby-in-Westmorland Cumbria England
Different oils for different phases of the engines life. Straight 100 when its new and running in. Moving to AD80 at 100+ hours and the parts are bedded in. Other types for other phases and engine types.
You can mix the oils but its a kinda emergency thing (do it more in the bush than anywhere else) but then change the oil when back in civilization.
h-r
You can mix the oils but its a kinda emergency thing (do it more in the bush than anywhere else) but then change the oil when back in civilization.
h-r
Better red than ...
Joined: Aug 2004
Aviation Qualifications: CPL
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From: Appleby-in-Westmorland Cumbria England
I wuz referring to my flying adventures in Australia, you cad!
(anyway on the 'Man Orr' they'd steal your skids before you had time to get the chip fat in the sump)
h-r
(anyway on the 'Man Orr' they'd steal your skids before you had time to get the chip fat in the sump)
h-r
Avoid imitations
Joined: Nov 2000
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From: Wandering the FIR and cyberspace often at highly unsociable times
Yes, when delivering goods by road up there you need two folks - one to take them to the house and one to guard the van! 
Joined: Mar 2000
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From: Arizona USA
Ram Aircraft in Waco Texas, which builds mighty fine engines has particular thoughts on aircraft oil, and its use...
http://www.ramaircraft.com/Maintenan...mendations.htm
http://www.ramaircraft.com/Maintenan...mendations.htm
