Yes I know it's a bit of a n00b question but it's something i've been wondering about for yonks.
I got a bit lazy so instead of draining all the oil out i just put in an extra 1 litre top up.
Now the oil i put in is different to what i had, which was shell helix ultra.
I put in 20-50 valvoline.

Now is it really that bad to mix oils without draining? :confused:

Cheers :thumbsup:

http://www.singlesplaces.com/outraged.gif

As long as they're the same thickness (same numbers eg. 20-50) and they're both the same type (ie. both synthetic, or both non-synthetic) there shouldn't be any major issues.
Might get abit more complicated when you mix different types though.

It was one of my questions a while back,

http://www.aussiemagna.com/forums/showthread.php?t=15861&highlight=mixing+oil


Whilst it can be done, and the engine oils are usually made the same (to work together) it shouldn't cause any damage or anything, but some ppl have had good+bad experiences so it makes you wonder...

Personally I would just do a fresh, oil change-over, including the filter, just to be safe and keep the engine happy.

Cheers guys!
Thanks for the link :D

I put new oil in every two weeks.

Its damn leaky :P

Ive never had problems with mixing oils but i always use 20W 50 and i never buy cheap crap.

I put new oil in every two weeks.

Its damn leaky :P

Ive never had problems with mixing oils but i always use 20W 50 and i never buy cheap crap.
New oil every 2 weeks!!
Fix that leak!! Are you nuts!! :shock:

maybe he means he's topping it up every two weeks?

Yes I know it's a bit of a n00b question but it's something i've been wondering about for yonks.
I got a bit lazy so instead of draining all the oil out i just put in an extra 1 litre top up.
Now the oil i put in is different to what i had, which was shell helix ultra.
I put in 20-50 valvoline.


Its not 'bad'... but ideally, you shouldnt.

Ummm and isnt helix ultra a 5w oil? :confused: You shouldnt have put 20w in with that. :doubt:

Try not to mix: -different weight oils
-and different types (ie, mineral, semi-syn & full syn).

Try not to mix: -different weight oils

why not?

If I wanted a 30wt and only had 1 can of 20wt and 1 can of 40wt... mix both 1:1 to get 30!!


-and different types (ie, mineral, semi-syn & full syn).

umm... semi-synth = synthetic + mineral oils


The ONLY fluids you cannot 'mix' in your car is Ester vs Silicone brake fluids.

Surely couldnt be too bad i did it by accident when i first bought my car (topped it up from half with mineral) with synthetic already in, but upon realising and inspecting a week later nothing had happened to the engine or anything, just to make sure i drained it and completely filled it with synthetic.

maybe he means he's topping it up every two weeks?

I don't mean top it up.

I go through a lot of oil.

Valve stem seals are gone, no gasket bar the head gasket on the entire car is whole and so it leaks constantly.

I got quoted 1000 to fix it.

Too much to spend on a $500 car.

So i just let it leak.

You should work out how long it's going to take you to spend that 1000 on oil.



I don't mean top it up.

I go through a lot of oil.

Valve stem seals are gone, no gasket bar the head gasket on the entire car is whole and so it leaks constantly.

I got quoted 1000 to fix it.

Too much to spend on a $500 car.

So i just let it leak.

Get some Nulon Engine Stop Leak. This is differnt to Stop smoke or products from other comanies as it does not work as a thickener. It actually makes the seals more supple, reducing or even stopping leakage. Worked for a friend of mine (that sounds so cliche doesn't it) so yeah, you should try it! It costs around $10 at Supercheap auto. This is different to Nulon Stop Smoke, which prime purpose is to stop smoke.

The other recommended product to use with Engine Stop Leak is Worn Engine Treatment, but it is not a necessity. That is also $10 but needs to be added at each oil change. Engine stop leak only needs to be added once.

http://www.nulon.com.au/products.php?productId=esl

Okay, so it won't stop all your leaks, but it will slow them down! It will probably negate the need for most of the work on your engine, except for the gasket. Thats around $130 or so to replace with labour etc. If you knew how to do it youself it would be a cheap exercise :)