Mixing Shell with Castrol

[Kern47]

Could be opening a can of worms here, and I've done a bit of research but not found anything conclusive (obviously).

I'm going to be doing an oil change and I've got 2 litres spare of Castrol Edge 10w60. Although for this one I'm tempted to try out the Shell Helix Racing instead (pretty sure it's what BMW are using now anyway) given that it's slightly cheaper.

I'd rather not have to buy 7 plus litres of new oil when I've already got 2 litres left from the last one... So does anyone see any obvious reason as to why I couldn't add 5 litres of shell, and then finish the rest off with the castrol? Still with some to spare for top ups?

Usually I'd just avoid that on the grounds of 'good practice', but I always just end up with half empty bottles of oil lying around from previous cars or because I change the oil grade/make.

Any input appreciated

Cheers

 

[mr wilks]

I can't see mixing having adverse effects but fundamentally oil does such a important job why would you want to scrimp :? imo oil choice l is more important than fuel choice
Just £63 for 6 litres of finest CFS Millers https://www.ebay.co.uk/itm/Car-Engine-Oil-Service-Kit-Pack-6-LITRES-Millers-CFS-10w-60-full-synth-6L/182524386043?hash=item2a7f4d1afb:g:1IcAAOSwpkFY6z6Y surely your car is worth that :wink:

 

[srhutch]

Personally I wouldn’t mix it. As Andy says why scrimp on the most important part of the engine.

Either by 5litres of Castrol or 7 of shell or A N other.

 

[R60BBA]

You’ll be fine.

When I had an oil leak (due to CPV) I couldn’t get my hands on Castrol and so I was forced to buy M Twin Power Turbo (Shell Helix Ultra Racing) from main dealer and had no issues.

However like Mr Wilks mentioned, why cheap out on oil on such a highly strung S54 engine?

Personally I’m a Castrol man through and through.

Check OpieOils for good deals / discounts.

 

[Mr Tidy]

BMW have gone over to Shell - even though all my 7 BMWs have had a Castrol logo on the oil filler cap! :?

My local BMW Indy said the change happened because Castrol wouldn't supply it in containers without a Castrol logo on them, but Shell would!

I'd fill it with 1 brand of your choice, and just use the Castrol for top-ups.

 

[Kern47]

BMW have gone over to Shell - even though all my 7 BMWs have had a Castrol logo on the oil filler cap! :?

My local BMW Indy said the change happened because Castrol wouldn't supply it in containers without a Castrol logo on them, but Shell would!

I'd fill it with 1 brand of your choice, and just use the Castrol for top-ups.

Yeah I'm gonna do that I think... Like i said, i never really liked the idea of doing things like that usually. Just dont want to throw oil away or have it sitting around for ever, suppose keeping the castrol for top ups will hopefully see it gone eventually.

 

[andyf1140]

It's going to make no difference they are both go quality oils of the same grade and specification

 

[ph001]

Agreed, you'd have to be absolutely paranoid to worry about mixing those two. Same grade and specs pretty much, and both approved.

 

[Matt.13]

I would not worry about mixing it to be honest. As already said both are decent oils.

 

[Kern47]

Yeah tbh that was my thinking. Like the only thing I'm doing is mixing the additives, which unless any of them react and cause it to solidify... I think I should be alright

But I've bought 7 litres of shell anyway, so I'll just see what I feel like doing on the day when I'm changing it.

Cheers

 

[mad4slalom]

Funny isnt it , a lot of us on here are always looking to do what is best for our z’s or at least what we think is best.
I too , when doing an oilchange wouldnt mix brands even of reccomended ones, just because it doesnt feel right, whilst feeling also that if they both meet the spec and are reputable brands there would be no problem whatsoever, once the cocktail has gone around the system a few times and been mixed and coloured a bit by combustion then its all one and the same. Also if its alright to use odd brands for topping up then its really no different to doing it in the first place, its not like the engine is going to only burn off the one used for topping up therefore leaving the original oil untouched is it ? As others have said, it just doesnt feel right. And as we all know, half the fun of owning and running a special car is the thrill of pampering it, and I must admit I enjoy spending money on mine , little things like ordering the correct clips for the airbox to throttle body pipes when I know jubilee clips are just as good and reuseable, but feels like it is skimping, and not original,now I have to buy the correct tool for the clips, but again I enjoy searching for one . Thats the purpose of a hobby car, its a thing you enjoy tinkering and fettling and knowing that in most instances you will do a better or at least more attentive job than a third party will do to time constraints.

 

[mad4slalom]

Agreed, you'd have to be absolutely paranoid to worry about mixing those two. Same grade and specs pretty much, and both approved.

and quite possibly made in the esso factory similar to when it came out that swatch were producing movements for rolex and other top brands

 

[Z4hid]

And as we all know, half the fun of owning and running a special car is the thrill of pampering it, and I must admit I enjoy spending money on mine , little things like ordering the correct clips for the airbox to throttle body pipes when I know jubilee clips are just as good and reuseable, but feels like it is skimping, and not original,now I have to buy the correct tool for the clips, but again I enjoy searching for one . Thats the purpose of a hobby car, its a thing you enjoy tinkering and fettling and knowing that in most instances you will do a better or at least more attentive job than a third party will do to time constraints.

I and many others here 100% agree with that!

 

[Gustavo7]

How much are you actually saving?

Different oil additives in same oil grade can still interact with each other, causing foaming as an example.

I’ve learned my lesson many many moons ago: stopping for fuel, noticed that the oil level on my Clio Williams (2.0L 150bhp) was getting lower than normal (there’s an oil level gauge) so rather than keeping the journey as it was, get home and top up I decided to get a 1L bottle of same grade oil at that petrol station. I was using Millers oil and topped up with Castrol, soon after that the hydraulic cam followers started to be noisy. (Tack tack tack noise)

It all went away after flushing the engine and putting new oil again.

For the sake of £20? I would risk mixing anything!