Old topic new question on suitable engine oil for a CDt

[bendrick]

At the risk of setting off a 20 pager and groans of "Here we go again"

What are the current thoughts of forum members on a suitable oil for a 75 diesel oil change that I intend to have a go at for the first time? ( normally pay a garage to do it but thought I'd have a go myself after all these years )

I have read up on some old threads yesterday after reading my handbook which says 10w40 or 15w40 Acea A3 & B3 and was surprised to read on this forum that this had been superceded in later years handbooks by advice that 5w40 oil is more suitable especially if the majority of your journeys are shortish round town jobs which mine are with the odd longer trip thrown in here and there.

As expected there were some vociferous arguments in the older threads as to whether the later advice and that issued by BMW rather than the old Rover group was correct in it's updating or not.

So whats the current thinking?

[macafee2]

I'm a Mobil 1 fan, 10/40.

You are right this will set of lots of opinions about which oil to use and the reasons why.

I'm not sure you will be any the more sure of which oil to use afterwards

macafee2

[bendrick]

Originally Posted by macafee2

I'm a Mobil 1 fan, 10/40.

You are right this will set of lots of opinions about which oil to use and the reasons why.

I'm not sure you will be any the more sure of which oil to use afterwards

macafee2

Well I'm more interested in the merits of the 5w40 versus 10w40 thing to be honest, I'm sure that most general brands are fine.

But if there is a perceived benefit of using 5w40 for more round town use then I'm in.

[Dorset Bob]

I have just keying in my car reg on the Mobil Oil finder
https://lubes.mobil.com/uk-english-l...which-oil.aspx

They recommend 0w40 for ultimate protection and 5w40 for everyday protection.

[T-Cut]

Originally Posted by bendrick

- - -was surprised to read on this forum that this had been superceded in later years handbooks by advice that 5w40 oil is more suitable - - -

This is from the last Handbook MGR issued:





The ACEA specs are probably more important than the viscoity, which can be almost any range typically encountered. Everyone has their favoured brand but the ACEA is definitive for performance.


TC

[Arctic]

TRIPLE QX Semi Synthetic Engine Oil - 10W-40 - 5ltr


Triple QX Premium 10W-40 Semi Synthetic motor oil is blended in UK with the highest quality base stocks and advance additive technology. It meets the performance levels and specifications for the vehicles requiring this oil. Triple QX motor oil provides optimum engine performance, improved fuel economy and reduced exhaust emissions.

• Benefits:
• Excellent Low temperature fluidity providing immediate circulation after cold starting
• Fuel saving capability due to low viscosity characteristics
• Low volatility due to part synthetic base stocks
• Outstanding engine cleanliness and protection
• Catalyst compatible
• Specifications: ACEA A3/B4, API SL/CF. MB 229.1, VW 501.01/505.00

https://www.carparts4less.co.uk/cp4l...6011&0&cc5_245

Euro carparts. use WEEKEND37 code for the discount.

https://www.eurocarparts.com/basket

Change the oil every 6 months whatever mileage & do the oil filter every 12months with the second oil change of the year, so lets say spring them Autumn.

[macafee2]

is 0/40 thinner then 5/40 which is thinner then 10/40?
the numbers being relative to the operating/protection temperatures?

For me not thrashing a cold engine also makes me feel that I am helping to protect the engine

macafee2

[MSS]

Either 5W40 or 10W40 will be fine in the UK climate. In all probability, you will not notice any material difference over the expected life of your car.

As for make - Millers XF, Shell Ultra or Mobile 1 treat the car well alongside a CTEK charger. Personally, I could not inflict cheap peasant oil on any of my cars!

[gadget1960]

Originally Posted by Dorset Bob

I have just keying in my car reg on the Mobil Oil finder
https://lubes.mobil.com/uk-english-l...which-oil.aspx

They recommend 0w40 for ultimate protection and 5w40 for everyday protection.

I would want my engine 'ultimately' protected 'everyday' tbh! (why the choice??)
Oil manufacturers .... all smoke 'n' mirrors and sales Bu****it. What exactly is the difference between 'everyday protection and 'ultimate' protection? Surely it's more important to get the correct grade of oil to start with and to change it according to driving habits and conditions!?
Having said that, a good quality oil that meets ACEA B3 in either 5w40 / 10w40 is all that's required for my 75 cdt in most conditions of driving in the UK (temps wise). I change mine fairly often as my journeys tend to be shorter than I would ideally like.

[COLVERT]

There is a difference between 5w40 and 10w40 for general use.

One is a lot dearer than the other.--

Apart from that, you are not really going to notice much difference unless you are running your car at minus temperatures.--