Any difference in oils for Diesels?? @ ExplorOz

AnswerID: 259234 Submitted: Tuesday, Aug 28, 2007 at 16:01

MEMBER - Darian (SA) replied:

As I know it, the grade and the viscosity are the main factors it seems - then you choose the brand. Grades change for the various engine types - all to do with what the manufacturer recommends - fuel types mean a lot too I guess. Isuzu specify a CG-4 grade for my Jackaroo TD, with a range of viscosities that can suit varying temperature zones. I use Castrol Magnatec 10W-40 but there a quite a few others makes that would be suitable. There are a few expert sites on the topic - eg.
http://www.carbibles.com/engineoil_bible.html

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When I'm too old to travel the outback, I reckon I'll have everything just right ! The "house" ? - Main street, Windorah.

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FollowupID: 520733 Submitted: Tuesday, Aug 28, 2007 at 20:31

Cram posted:

I am new to Diesel motors but when I got my Disco TD5 earlier this year, the mechanic I rang in Newcastle, who has been dealing with Landrovers for years said, "make sure you use the right oil, if you don't you will have trouble." He uses and recommends Castrol Magnatec.

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AnswerID: 259235 Submitted: Tuesday, Aug 28, 2007 at 16:07

MEMBER - Darian (SA) replied:

Just looking at that bibles site - seems like the CG-4 designation would best be termed the 'category' (there's about 13 of them listed) - grade is still commonly used in reference to viscosity.

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When I'm too old to travel the outback, I reckon I'll have everything just right ! The "house" ? - Main street, Windorah.

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AnswerID: 259236 Submitted: Tuesday, Aug 28, 2007 at 16:13

Mainey (WA) replied:

Diesel's use 'different' oil to petrol engines, which can be seen in the oils technical specifications. The viscosity is not the main difference as often it's similar or the same.

That's why some oils are rated for "old" engines, some for "new" engines and some for "Diesel" engines which produce soot and require a cleaning agent added which is not in the oil for petrol engines.

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AnswerID: 259242 Submitted: Tuesday, Aug 28, 2007 at 16:39

True Blue replied:

Signman, just recently I asked my mechanic son whether he would service our D40 t/diesel Navara. Yes, and he would look up what the required grade of oil was required as specified by Nissan.

The son suggested that we run a fully synthetic oil which covered the grades required by Nissan. No worries I said, go for it.

And I'm glad I did. He chose Mobil 'Delvac 1' and we purchased 15 litres (enough for 2 oil changes) for $150 which I reckon is pretty damn good.

Well we changed the oil and pretty much changed the engine.
From cold it felt as if it had been driven for half an hour. Very smooth, much quieter, and pulled as though it had been warmed up. The mileage on the tank increased from 700ks (before warning light comes on) to over 790ks and the light still hadn't come on.

I thought how grouse is this? The oil exceeds the manufacturer's recommendations, makes the car perform better and much more economically in the process.

Check it out, I can't recommend this oil high enough.

Cheers, True Blue.

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FollowupID: 522226 Submitted: Friday, Sep 07, 2007 at 00:03

blown4by posted:

It might be worthwhile checking the Nissan handbook again because as general rule Nissan advise against fully synthetic oils in their diesel engines. For example on the ZD30 they advise against using any oil that exceeds CF-4 and there is a Nissan service bulletin that specifically warns against this. If they say in your handbook fully synthetic is OK well that is fine then, but if not it would be a shame to save a few cents on fuel consumption and then have to pay out big time for an engine rebuild. I am no lubrication engineer but in laymans terms it is to do with the higher compression pressures, piston ring materials and the fact the fully synthetic oils are in effect too effective at doing their job. This prevents the rings from bedding in properly and maintaining a good seal against the cylinders which then causes the cylinder bores to glaze up and the engine then starts to burn oil which is only reversible with an engine rebuild.

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AnswerID: 259262 Submitted: Tuesday, Aug 28, 2007 at 18:54

Member - Phil G (SA) replied:

Signman,
Firstly, a disclaimer - I'm no expert, but this is the way I see it and welcome any corrections.

The difference is in additives. Put simply, diesel oils have more detergents to handle soot better. Petrol engine oils also contain detergents, but its not as critical.

Your 1Hz is an old fashioned indirect injection diesel, so it produces a bit more soot than the modern direct injection diesels. You'd be better off with a diesel engine oil, as soot can lead to oil thickening.

Many diesel engine oils are marketed as mixed fleet - so can be used for petrol as well as diesel vehicles.

If cost is a major consideration, a 15W40 Ci-4 mixed fleet oil like Fuchs Universal HD , or Gulf Western Top Dog will be fine in your 1Hz. I buy them for under $80 for 20litres from the truck shops.

Cheers
Phil

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FollowupID: 520712 Submitted: Tuesday, Aug 28, 2007 at 19:09

Exploder posted:

Right, It's in the additive package in the oil.

Some oils can be used in both Petrol and diesel engines, Castrol, Penrite and Amsoil are the ones i can think of that have duel usage oil, i am sure other do as well.

I use a Amsoil Diesel oil in My Turbo Falcon as after talking with amsoil and doing some reading I decided it was the best Oil suited to my application.

Cheers.

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FollowupID: 520716 Submitted: Tuesday, Aug 28, 2007 at 19:39

Member - Phil G (SA) posted:

Exploder,
All the oil companies have mixed fleet oils. Thats what the majority of workshops (including dealers) use. Its always interesting to extract from the suited guy behind the counter exactly what oil they put in your diesel motor, and they sheepishly tell you its a CF grade something, that you paid top dollar for.

But most of the newer petrol motors want a 5W30 or 10W30 these days, so you can't use the same oils.

Cheers
phil

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AnswerID: 259323 Submitted: Wednesday, Aug 29, 2007 at 04:34

Member - Bucky (VIC) replied:

There are a million reasons hy you shouold type Engine OIL into the the forum search bar, and look what happens.
A million different Ideas, but what they are basically telling you is to read your owners manual, and only use the recomended oil, with the specifications.
That way you should never go too far wrong.

Cheers Mate

Bucky