Engine Oil; is mixing grades and brands a bad idea? 0W / 5W? Mobil 1 or Castrol Edge?

[mikeb2k2001]

Hello fellow Mini2 users, I was wondering if you all could give me a hand as I've been searching the site for a while now and have been looking at various shops to purchase some top up oil for my Mini One D (2004), which is running a little low.

I've previously topped up my Mini D with some Castrol 'Edge' 0w-30 bought from [evil] Halfords for just shy of £20. My dip stick is now perilously near the low end of the scale, so I've decided to go whole hog and buy a 5 Litre bottle of oil...

However, I entered my car registration on the Halfords website and it is says the recommended oil for my car is 5W-30? I also went over to Castrol's official website and entered my reg number, with it telling me that I need 0W-30 'Turbo Diesel Edge'. I'm now very confused as they state different variants of oil and I am hesitant to mix '0W & 5W'.
Also to add to the mix...Halfords are currently (time of print: October 2009) running a promotion on Mobil 1's oils, with 20% off...making it significantly cheaper than the Castrol counterpart. Also, after doing some extensive reading on this site, it seems that Mobil 1 is the superior oil? (But it just hasn't got the BMW affiliation/bias).

So essentially, I'm now very lost indeed and would really appreciate a discussion/answers to the following questions. So in essence:

1. Which oil should I use for a Mini One D 1.4 TDI - 0W-30 or 5W-30?! - If it's a specific one for the Diesel engine, then please state other model variants (such as cooper S recommendations, 1.6 petrol etc) oils to help future viewers with their decisions!
2. Is it safe to 'mix' variants, i.e. 0W-30 with 5W-30 if the other was previously used?
3. Can you mix brands? I.e. Castrol Edge was used in the past, would it safe to use Mobil 1?
4. Which brand would you recommend; Mobil 1 or Castrol?

I think it might be of some use to let you know that I live in the UK. I've noticed in some other posts that in the UK, it's recommended that we use 0W-30. If this is the case...why on earth are Halfords (one of the biggest national shops in the UK for car oils) telling us 5w! Please let me know if it doesn't matter...as at the moment, if the Mobil 1 5w could be used in conjunction with the 0w Castrol used previously...that'd save me a good £10!

Let me end with thanking you in advance for any information received and I’ll post some pictures of my Mini sometime soon if all goes well.

Cheers once again,
Mike.

[rburna]

u should b fine with either 0 or 5, and mixed together. the w only indicates the operating/starting temperature range. just stick with synthetic, and try not to mix synth with dino oil.

differences in brands r the additives they put into the oil to maintain longevity n the likes.

[DaFlake]

Unless somthing has changed, I believe that you should be using oil designed for diesel and not regular motor oil. Becasue we don't have that engine here in the USA, I can't be sure, but on my older diesel cars we used specific oil for them.

So... If someone would clarify this I would apreciate it. If I turn out to be right, you need to change your oil and filter immediatly as you could damage the engine running regular oil in there. It needs to be rated for both or diesel only.

As mentioned, you can mix the (w) portion. The 0w or 5w is the winter rating of the oil which shows how well it will hold its viscosity in colder climates. The other number is the weight of the oil and can't be mixed. Thus if you have 30 weight you should stay with 30 weight and not put 40 in. You can also mix brands but as mentioned do not mix dino with synthetic oil. Either brand you selected is a trust worthy brand.

[georgeshair]

If I can join in the debate, I took my 2001 MINI Cooper for an Inspection 1 a few weeks ago and they carried out an oil change using Shell Helix Plus 10W40. I've just been told by another garage that this is a partially synthetic oil, not fully synthetic, and could cause my engine to work harder.

What should I do? Should I go back to the original garage and ask them to do another oil change? I'm not sure where I stand legally if they haven't used the correct products for the car.

[DaFlake]

Quote: Originally Posted by georgeshair (original)

If I can join in the debate, I took my 2001 MINI Cooper for an Inspection 1 a few weeks ago and they carried out an oil change using Shell Helix Plus 10W40. I've just been told by another garage that this is a partially synthetic oil, not fully synthetic, and could cause my engine to work harder.

What should I do? Should I go back to the original garage and ask them to do another oil change? I'm not sure where I stand legally if they haven't used the correct products for the car.

Was it a MINI dealer? If it was, I would take it back and make them put the right oil in. You want fully synthetic in the car and 40 seems to be a bit thick for our cars.