Engine Oil

[alfadave]

My neighbour gave me 2 litres of Halfords Fully Synthetic engine oil. 5W/40.
But it says diesel oil on the bottle.

I wondered what the difference was between that and petrol engine oil.

Its maybe a bit thin for the Sud, but perhaps ok for my wifes Mazda 2 1.3 petrol?

[Veesix75]

The oils that start at 0/and 5/are for modern engines where tolerances are more accurate, eg smaller gaps.

I use 5/40 in the petrol Giulietta.

Older engines are usually 10/ cos the gaps are bigger and it needs thicker oil at cold start.

The higher number is for stability at high temps, hence I use 10/60 in the racer.

How old is the Mazda ? If it’s a relatively modern engine 10 to 15 years or so then it should be fine.

As an aside, my BMW’s used 5/30 from factory, but once higher miles I went to 5/40 and they drank less oil.

[alfadave]

Mazda 2 is 10 years old.

But what is the difference between diesel engine oil.......and petrol engine oil?

Maybe just a marketing tactic?

[Veesix75]

So long as it’s the right spec, yes.

Just check the API and SN spec to be sure, but I’d use it.

I think modern diesels started using the lower viscosities earlier than petrols so probably listed as diesel to stop someone using it in an older petrol?

Kev will probably know best as he will have probably put the same 80 gallon drum oil in different cars 100’s of times when servicing the modern crap at work

But as above I’d use it.

[KevJTD]

Most diesel specific oils will have a detergent in that's not in the petrol only spec ones, having said that a lot of grades will suit both.
I don't tend to worry on my own stuff but the newer cars we get in from the likes of Enterprise and Lease hire companies we have to get the specific grade in for, or be open to getting sued if something goes wrong and we get blamed for using the wrong oil! So no big 45 gallon drums on ours Tim

If you want to check then Shell have a handy site, we use Mobil now but this is similar to the Shell one we used to use

https://www.shell.co.uk/motorist/engine ... 3J5PWNhcnM

For what it's worth I'm sure you'll be fine if it's 9n the same grade.
There is a certain amount of marketting in it I reckon as the same engine used in Ford and Peugeot engines use the same grade but they have differing spec as in FE for the Ford engines which when the same engine is in the PSA group stuff now inc the Vauxhall they don't have that FE spec but something else which escapes me just now, so there has to be a certain amount of BS to it.