Hi everyone,

 

Firstly, a thank you to you all for sharing your knowledge and experiences with these engines over the years. I've been a long-time 'lurker' on this forum after buying my CAVE twincharger 18 months ago and have found it an invaluable source of info.

 

As a bit of backstory, my CAVE was originally an oil drinker. I did find moving to 5w40 and using manual shifting on the DSG helped slow down consumption. I've since had the engine overhauled with (amongst other things) the improved Kolbenschmidt pistons, CAVD oil jets, and latest ECU software. It is currently running on 5w30 and shows no signs of buning oil after nearly 2000 miles post-overhaul.

 

My question is - why is 5w40 is so often recommended as the preferred oil grade for this engine? Is it purely due to the reduced consumption in oil-thirsty examples, or are there other benefits over 5w30 even for a non-oil-burner?

 

I ask mainly because VW 504.00 spec appears to be superior to 502.00 in every way on paper, and I'm yet to see a 5w40 grade oil that meets 504.00. The 'longlife' aspect isn't a concern, as I've been changing the oil and filter change every six months under my ownership and will continue to do so.

 

I appreciate any insight you might be able to give. I've spent quite a lot on this engine trying to get it the way it should have been from the factory and want to do all I can to keep it running healthily! Thank you.

 

 

8 minutes ago, boycie said:

why is 5w40 is so often recommended as the preferred oil grade for this engine?

Primarily because @Rooted thinks it's better, and says it most days, I think.  😁

@boycie  What is it that makes Long Life oil appear superior? 

 

I think it is best not to use the Long Life because actually it is in your CAVE engines that were first given the Code for Fixed Service Oil & Filter changes.

Plenty oil users have used less oil when 5w 40 FS is used instead of 5w 30 FS III.

Also ran the oil a couple of degrees C lower. 

 

The issue with the CAVE engines was and can be bore wash. & the 1 spark plug that gets fouled and cooked.

The prescribed fuel was 98 ron, (yes they an run 95 unleaded.)  In the UK E5 will be 97 or 99 ron min.  With additives and detergents.

Then the oil has additives, anti foamers, detergents etc.   Maybe you can have too much of a good thing. 

Higher octane fuel with cleaners and the oil. 

 

But the choice is the owners. 

Edited 18 April, 20242 yr by Rooted

2 hours ago, boycie said:

Hi everyone,

 

Firstly, a thank you to you all for sharing your knowledge and experiences with these engines over the years. I've been a long-time 'lurker' on this forum after buying my CAVE twincharger 18 months ago and have found it an invaluable source of info.

 

As a bit of backstory, my CAVE was originally an oil drinker. I did find moving to 5w40 and using manual shifting on the DSG helped slow down consumption. I've since had the engine overhauled with (amongst other things) the improved Kolbenschmidt pistons, CAVD oil jets, and latest ECU software. It is currently running on 5w30 and shows no signs of buning oil after nearly 2000 miles post-overhaul.

 

My question is - why is 5w40 is so often recommended as the preferred oil grade for this engine? Is it purely due to the reduced consumption in oil-thirsty examples, or are there other benefits over 5w30 even for a non-oil-burner?

 

I ask mainly because VW 504.00 spec appears to be superior to 502.00 in every way on paper, and I'm yet to see a 5w40 grade oil that meets 504.00. The 'longlife' aspect isn't a concern, as I've been changing the oil and filter change every six months under my ownership and will continue to do so.

 

I appreciate any insight you might be able to give. I've spent quite a lot on this engine trying to get it the way it should have been from the factory and want to do all I can to keep it running healthily! Thank you.

 

If your engine does not use oil then you can stick with 504 spec since there's absolutely no reason to change.

3 hours ago, boycie said:

why is 5w40 is so often recommended as the preferred oil grade for this engine? Is it purely due to the reduced consumption in oil-thirsty examples, or are there other benefits over 5w30

Well the only intrinsic "benefit" of  5W40 over 5W30 is that the viscosity of 5W40 changes more slowly with increasing temperature. There is no direct relationship between viscosity and a VW 599.00 specification.

Some people are obsessed with viscosity, they erroneously believe that it somehow makes up for slack tolerances in their engine, some people also believe that changing gearbox oil will magically repair their worn synchro rings!

The fundamental design, manufacturing and materials and software issues / components and consumables caused the reason for people doing things that cost no extra to try and if worked then good.

The Engineers were doing little in the way of giving advice, and as for mechanics, they were the cause of so much issues saying the oil use was within tolerances when they were nothing like it. 

 

Using VW502 00 / 5w 40 FS never caused issues with the first CAVE engines that needed rebuilds or replaced and had the code for Fixed Oil & Filter services.

Using VW 504 00 / 507 00 , 5w 30 FS III never benefited a CAVE or a CTHE if they were on fixed service intervals and not many did oil & filter changes on Variable mileages.

 

If the engine uses no oil and is problem free then why not use the Long Life oil.  What is the worst that can happen?  Likely nothing. 

6 hours ago, Rooted said:

What is it that makes Long Life oil appear superior? 

 

@Rooted I've seen a few sources stating VW 504 is a newer and more demanding spec to meet than VW 502, such as VW 507.00, VW 504.00, etc: Volkswagen Motor Oil Specifications Explained - oilspecifications.org which includes the following:

 

 

These sources give me the impression 504 is preferred in all instances, but that you can 'get away with' using 502 spec as long as you don't exceed fixed service intervals.

 

Your comment about bore wash is interesting though, as well as the description (in the links you posted) of 502 spec oil being preferred in 'arduous/strenuous conditions'... such as in a highly-strung twincharged engine. It does make me wonder if 502 spec oil is seen as more 'robust' and able to resist heat degradation?

 

As I said, just genuinely curious as to the science behind the debate. Luckily, consumption does not seem to be an issue for me with a 504 spec 5w30, but if a 502 spec 5w40 will serve my CAVE engine better in the long run then it's worth considering a switch.

 

Is it the cylinder 4 spark plug that tends to get coked/fouled, by the way?

 

Thanks for the replies everyone, much appreciated.

 

 

 

There's actually another pair of VW specs visible on erWin if you make a login and then click on the Approved oils link on the homepage.

 

VW 508 88, and VW509 99.

 

There are currently 19 oils showing as approved to these, all SAE 5W-40.

 

I know nothing more about them nor the reason they exist; but to set off speculation, the genuine VW one is called 'maxi performance'. 

Perhaps they've taken note of what George has been telling us?

 

Go to a Skoda parts counter and ask, maybe?

Doubt they're cheap.

Edited 18 April, 20242 yr by Breezy_Pete

Not those.

04367032402255.pdf

Edited 18 April, 20242 yr by Rooted