Petrol or diesel engine oil?

[Richardluff]

Assuming you get the right grade of oil, does it matter whether I use a product described as an oil for petrol engines for my Golf TDI (diesel) car?

 

[HDi fun]

There's much more to it than just the grade, or viscosity. But if the API and ACEA specs are suitable then you'll be absolutely fine.

Check the VW recommendation and get an oil with that approval marking to be totally safe.

Many oil makers are producing multi-purpose engine oils now, such is the state of oil technology.

 

[oilman]

It depends on the engine in the Golfs. If it's a PD engined one, it needs an oil that meets the VW505.01 or 507.00 spec or there is a lot of wear on the cam. If it has a DPF, it can only use a 507.00 spec oil. If it's pre-PD engines, it's not that fussy and 5w-40 or 10w-40 is fine.

 

[HDi fun]

It depends on the engine in the Golfs. If it's a PD engined one, it needs an oil that meets the VW505.01 or 507.00 spec or there is a lot of wear on the cam. If it has a DPF, it can only use a 507.00 spec oil. If it's pre-PD engines, it's not that fussy and 5w-40 or 10w-40 is fine.

Presumably because the PD engines use the (only) camshaft to not only operate the injectors but to create the fuel pressure as well?

Is this the same reason that some VAG PD engines are having cam belts replaced every 18,000 miles?

 

[oilman]

Presumably because the PD engines use the (only) camshaft to not only operate the injectors but to create the fuel pressure as well?

That is correct.

Is this the same reason that some VAG PD engines are having cam belts replaced every 18,000 miles?

Not sure on that one.

 

[HDi fun]

Thanks - that's put me out of my misery. Not that I'm likely to buy a PD car anyway - VAG has given in to the commercial attraction of common rail injection, despite the fact that the PD system is superior in many ways.

 

[jarrus]

Higher fuel pressure is one of them,
Simpler design,good for making loads of power, but emissions and also the fact they were the only manufacture that were using it so the cost of devolpement is also high when CR technology is already there....

 

[Richard1]

Diesel oils are designed for the higher pressures on cams, bearings, rings, etc. they have ta least 50% more anti-wear additives than gasoline only oils. Then also have 50% more detergent/dispersant, keeping the soot from clinging to the parts where the flow reduces speed (valve train and covers, oil pan, etc.)

They are also good for older engines with flat tappet valve trains since the extra anti-wear protects the sliding action of that valve train.

 

[jarrus]

Ok then, maybe you can help me here then,

I used to use Castrol EDGE turbo diesel 5w-40 fully synthetic

Now I use Fuchs Titan Pro Race S 5w-40 also fully synthetic
I was told that even though the Fuchs wasn't a diesel specific oil that it will be a better lubricant because of it's better base stock. The Fuchs is an ester based stock oil and the Castrol is PAO based I think. You're thoughts would be appreciated on this matter.

My car is a 1998 Peugeot 306 1.9 Turbo Diesel, (XUD9TE/DHY is the engine code)

 

[Richard1]

Ok then, maybe you can help me here then,

I used to use Castrol EDGE turbo diesel 5w-40 fully synthetic

Now I use Fuchs Titan Pro Race S 5w-40 also fully synthetic
I was told that even though the Fuchs wasn't a diesel specific oil that it will be a better lubricant because of it's better base stock. The Fuchs is an ester based stock oil and the Castrol is PAO based I think. You're thoughts would be appreciated on this matter.

My car is a 1998 Peugeot 306 1.9 Turbo Diesel, (XUD9TE/DHY is the engine code)

Neither would be my preference. Granted it is not a severe application, but low in additives. Synthetic base oils are better than normal, and Castrol is probably a group III vs Fuchs claiming ester. Some esters are always used with PAO to increase the solvency. They may have a combination of various oils in there.

Base oil gives you hydrodynamic lubrication. Best for the bearings and oil coated areas. when you push through that film, as in high acceleration or low rpm pressure against the bearings or in any case the rings above the oil control rings, or a sliding valve train, you depend on boundary lubrication. That is provided by additives, primarily ZDDP.

Of the two, the Fuchs is the better oil in my opinion. We don't have either around here, so I can only evaluate the data on line.

If you want to read up on the details behind it, take a look at this article
http://www.widman.biz/Corvair/English/Links/Oil.html

I wrote it for the Corvair community, but it applies to all flat tappets and diesels.

 

[HDi fun]

The pressures on cam/follower interfaces shouldn't differ much between petrol and diesel engines.

The Brake Mean Effective Cylinder Pressure is higher with a diesel engine and as such the bores and rings are likely to wear more severely on the power stroke side of the bores.

But, then again, diesels generally are operated at lower rpms than petrol engines so this is perhaps not so severe as it might first appear.

Castrol's Edge range is fine (and approved) for many applications - I use the stuff in my E39 BMW, which is a petrol model. If it was a 530d or 535d I'd probably use AMSOIL's diesel specific formulation, or one of Fuch's or Silkolene's ester based synthetics.

Zinc di-phosphates and sulfated ash are best avoided with particle filter equipped diesels.

The oil industry for retail and workshop applications changes almost as quickly as the IT industry, so it's very very hard to be absolute and accurate. At least, not for very long

 

[jarrus]

I did ask oilman about AMSOIL and he said it's good but very expensive compared to the likes of Fuchs/Silkolene the Fuchs is slightly better because of the better base stock.

I am thinking about have my waste oil analised next time I change it to see what condition my engine is in and what sort of state the oil is in when it leaves the engine so I can see what kind of intervals are needed.

 

[HDi fun]

I did ask oilman about AMSOIL and he said it's good but very expensive compared to the likes of Fuchs/Silkolene the Fuchs is slightly better because of the better base stock.

I am thinking about have my waste oil analised next time I change it to see what condition my engine is in and what sort of state the oil is in when it leaves the engine so I can see what kind of intervals are needed.

Oil analysis by a lab is a very very good thing to do.

 

[Richard1]

If you do it and I don't see it, PM me and I'll offer opinions. I've done somewhere between 4000 and 5000 samples.

 

[HDi fun]

If you do it and I don't see it, PM me and I'll offer opinions. I've done somewhere between 4000 and 5000 samples.

That's a kind offer and thankyou. When I next need an oil service I'll forward an oil sample directly to you. Thanks in advance,

Kind regards,

Paul Anderson.

 

[Richard1]

I don't do the lab work, but am pretty good on the analysis of the data. I sent all my samples to Arizona.

I should add that it is getting more complicated these days. It helps of the lab also has a sample of the fresh oil, since some of the new oils use silicon anti-foam (silicon used to be a dead give-away that there was dirt in it) and Sodium Sulfonate detergent (sodium used to be mean water).

 

[HDi fun]

Sodium is a soft metallic element. It does react violently with water.