Ok to mix 'petrol engine' 15W-40 oil and 'Diesel Engine' 15W-40 oil?

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

Ok might be a slightly noob question here but I dont really get the various oil specs. I need to top up my oil, but in my sickness induced fug I've walked out with 1 litre of 'petrol spec' oil. So my question is can I top up or should I go back and swap? Or is it just a bit of marketing spiel?

Same Brand, both Semi-synth, both 15W-40 (so no issues there) but one is labelled as API SN 'formulated for petrol' and one is API CI-4 'formulated for Diesel'.

[BiLLz0r Advanced Member Find all posts View Profile Close BiLLz0r]

I googled it and mixed opinions. Depends how much you need to top up I guess. I wouldn't do the whole liter but a couple hundred ml should be fine.

[t303 Senior Member Find all posts View Profile Close t303]

I wouldn't be too concerned, many oils are mixed fleet like Delo400 I use. The additive package will be different and diesel oil is usually high on detergent, but a top up wouldn't be a problem.

[GEEEXL Member Find all posts View Profile Close GEEEXL]

id be more worried why you need to top it up

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

id be more worried why you need to top it up

My stuff up when I changed the oil & I'm short. I leave Sydney for the Hay River track in a week.

[Guest Close Guest]

For peace of mind, why not go back and swap it? Then you won't have to worry about it during the trip.

[Gasmanjc Junior Member Find all posts View Profile Close Gasmanjc]

If going on a trip I would certainly swap it

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

Just trying to save myself the trip. . I'm at home with man flu, looking after a kid with boy flu, and a cranky toddler whilst SWMBO is away on a girls weekend. Been doing some googling today and it seems it's ok for 'light duty diesel' so I'm figuring a few hundred mls in the 6.5 litres won't worry it too much.

Thanks for the input

[VKPrado Avid PP Poster! Find all posts View Profile Close VKPrado]

Good to see you are getting the flu out of the way before you go away. Great planning.

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

Always thinking ahead, that's me...

[stanmiko Member Find all posts View Profile Close stanmiko]

Simple answer to the OP's question is NO.

Unless you can ascertain the two oils' ACEA rating is compatible for diesel engines.

Here's a boring, but extremely important, read on why some oils should not be used in some engines, regardless of how small a quantity is 'topped up'.

https://www.acea.be/uploads/publicat..._Sequences.pdf

Check the ACEA requirement of YOUR engine. If the 'top-up' oil does not meet that standard EXACTLY, or does not have the appropriate ACEA rating, then I would not be using it. For example, if your vehicle DOES NOT have a DPF then the use of ACEA C1-C4 rated oils is unsuitable, as they are designed specifically as low ash (SAPS) and may not provide the correct lubrication qualities required by YOUR engine. If your vehicle's engine specifies an oil with ACEA rating of B3 or B4, for example, a Cx rated oil is unsuitable.