Engine oil top up

14th May 2016, 22:21

Topped my engine oil up with 10w40 because it's all I had in the boot and I was desperate. But the oil in there is 5w40. Can mixing the 2 grades cause a problem? Will be changing it anyway with a new oil filter for a peace of mind.

14th May 2016, 22:44

Shouldn't worry about it. Better enough oil than a new invented 7.5w mixture.

Doesn't harm the engine, filter wouldn't affect it though.

15th May 2016, 21:43

Good, I changed the oil and filter for a peice of mind. Got an oil leak so I'm getting through a litre of oil every 3-4 weeks

not sure where the leak is though

16th May 2016, 07:39

Look at it this way, some oil of the incorrect grade is far by far better than no oil of any grade

16th May 2016, 21:58

Quote:

Originally Posted by Phaeton

Look at it this way, some oil of the incorrect grade is far by far better than no oil of any grade

True I was just wondering about mixing grades.

16th May 2016, 23:27

No harm at all.

17th May 2016, 09:55

mixing TYPES of oil is the problem --and this is from long time ago when you had mineral based oils +non mineral based oils --like "castrol R"--
they turned into jelly when mixed
but all modern oils mix fine even synthetic and non synthetic mix ok

Its amazing how old and out of date things live on --must be 40years at least since last mixing oils was a problem --
there were vegetable based oils like castrol R --then oils changed to detergent types --all oils are detergent type now

we are talking about motor oils and not aircraft oils /supercharger traction oils or other such exoctic types

that was the other problem you used to get in the late 60,s when you changed an old car from "castrol XL" --or something like that to a modern detergent based oil
which would clean inside of engine and lift all the crud out of sump and off sides of pistons etc .
the nice old minor 1000 --which ran fine on old type oil--change it to new detergent type and pistons rattled +it smoked ,just because all the crap that was making up the clearances in bores and bearing s was now gone --
so yes with old engines and mineral based non detergent oils changing to a mineral based detergent type was a problem .

all oils have been detergent type since late 60,s /1970 for sure --

this is also why modern engines last so long, oils are so much better that when you lift the head ,there is no bore lip --and you can see the orginal boring marks ,but now polished over ----that is also why when fitting new rings in old bore you must "de glaze the bore" so new rings can bed in
all your engine wear happens in first few seconds of start up while oil circulates and getting up to running temp