I've read the article on oil; however, being somewhat *nally retentive, I want to make sure I buy the right stuff for my vehicle.

It's an '01 Octavia Diesel on a QG1 (longlife) service interval.

Haynes manual and Service Schedule recommend VW 506 00, which, from my understanding relates to 5W40; however, my understanding is also that 506 00 is superceded by 507 00, but 507 00 oils are 5W30.

Which do I buy: a 5W30 or 5W40?

Thanks

Personally I would stick with a 40 if that's what the manual/handbook says. You can always go lower on first number (5w to a 0w) as this just relates to the thickness of the oil cold and a 0W will get round your engine a bit quicker than a 5W from a cold start. It's when you start changing a 40 weight to a 30 that you 'could' start running in to problems with oil leaks as it will be thinner at operating temperature than the 40.

i allways use VW quantum longlife 111 in this type engine its 50 700 5w30 for longlife servicing

if you change the interval to yearly 10k then i would use VW quantum platinum 5w40 this is suitable for all pd engines

If you want to continue with long life servicing you will have to use 507 spec long life oil or you could change to normal servicing and use 505.01 spec.

I believe that Vauhalls ( GM) sell a long life 505.01 oil but I would assume that this would not be approved by VAG for long life use in the event of any engine problem.

Ford used the PD engine in the Galaxy so sell PD oil certified to the correct standard but seriously it's £25 for 505 spec Quantum for fixed interval and £32 ish delivered for Quantum III long life which is VAG's own brand, considering the the dangers of cam wear its a no brainer and not an area you want to try and save £5 on. As to the weight you're fixating on the wrong part of the spec, weight is largely irrelevant in our climate, it's the standard it is certified to that's important.

Edited 31 March, 201313 yr by Avalon

For a petrol which is best to use? I have a bottle of 5w30 given to me but am I right in think 5w40 is better for petrol's?

Viscosity isn't the number you need to pay attention to, it's the certification to the relevant VW standard for your car that's relevant, look in the manual, it will tell you what 50x.0x oil you require, if the oil you have is certified to (that's not the same as 'meets' but that's another conversation) this spec it's all good. If it doesn't then don't use it.