Diesel oils-an interesting topic/selection!

Submitted: Tuesday, Jun 01, 2004 at 21:21
ThreadID: 13374 Views:4220 Replies:4 FollowUps:4
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Was just reading a couple of posts about what diesel oil is good for what age engine etc (ie CF, CG, CH, CI). Have heard that it is better to run a previous rating in older diesels, but having just gone to the Caltex website for a quick sticky, they of course say to run Delo 400 (CI-4) in everything from a 1980 model SD22 (Datsun 720) to current!! Seems they are keen to flog this stuff!

Just out of interest, I decided to run Delo 400 (just my own decision) in my intercooled TD42 GQ (80,000k's) about 35,000k's ago with changes @ every 5000k's. I had no knowledge of the possibility of increased oil consumption of a CI-4 oil in my '97 GQ so I guess it's a lucky thing that it hasn't used a drop. It does need the tappets doing now but I think it's noisy cause of the 50,000k interval not the oil? If anyone has a TD42 running CI-4 oil that's had a disaster, I would love to know-so I can switch...

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Reply By: basecamp15 - Tuesday, Jun 01, 2004 at 21:48

Tuesday, Jun 01, 2004 at 21:48
Can you explain what the tappets are and the cost of 'doing them'? I have a slight tapping noise at idle that isn't the usual diesel clatter. I'm not sure if it has something to do with the aircon as sometimes it goes when the AC cycles and other times it doesn't. Someone mentioned Tappets but I am not a mechanic.
AnswerID: 61270

Follow Up By: Muzza - Wednesday, Jun 02, 2004 at 17:44

Wednesday, Jun 02, 2004 at 17:44

Tappet noise is caused by too bigger gap between the valve rockers and valve stem. Nissan TD42's run mechanical lifters and not hydraulic, therefore they need to be adjusted using a feeler gauge to get the correct gap. The noise is sort of like a faint metal rattle (hard to describe!) I'm not sure how much a mechanic charges cause I do them myself. The service interval in the book says 20,000k's but that's a bit too close for my liking!

FollowupID: 322838

Follow Up By: basecamp15 - Wednesday, Jun 02, 2004 at 22:41

Wednesday, Jun 02, 2004 at 22:41
Thanks Muzza.
I reckon I'll be getting mine done then. It looks like I need to do the valve stems as I'm getting blue smoke on cold start so the tappets will need doing at the same time. I'll be doing the injectors then too I suppose. Just gotta get a bank loan first :)
Cheers, Mark.
FollowupID: 322893

Reply By: Member - Captain (WA) - Tuesday, Jun 01, 2004 at 22:42

Tuesday, Jun 01, 2004 at 22:42
Hi Muzza,

The Delo 400 oil is a very good, but be aware that it can actually "clean" your engine internals much better than an older oil. This can result in your oil being overladen with old deposits. But as you changed your oil every 5,000kms, you will have minimised any ill effects from the changeover and overall will probably help prolong the life of your engine with the newer grade oil.

Overall, a newer oil generally offers better protection to any engine. But just be aware when changing grades of oil after a long time to initially change the oil and filters frequently to ensure any old deposits do not overload your oil.

I doubt any modern oil would be a total "disaster", but the oil adage "oils ain't oils" is oh so true. Just look at all the recent posts about cheap diesel and the problems thats caused. But you have used top shelf stuff and will not be an issue.

Different brands of oils have different grades of additives, even though they still comply to the same oil spec ie CH-4. Even changing brands of oil in the same grade "can" have an effect. Its an area easily overlooked but one that can cause problems.

But it is FAR more of an issue when oil is not changed regularly. Manufacturers are specify longer service intervals these days, mainly to reduce fleet maintainance costs. The oil itself rarely 'wears out", it basically becomes contaminated (this is why ancillary bypass filters work well and extend the service interval between changes). Changing your oil, particuarly in a diesel, every 5,000kms is perhaps the cheapest and best insurance for your engine.


AnswerID: 61281

Follow Up By: wet feet - Wednesday, Jun 02, 2004 at 17:12

Wednesday, Jun 02, 2004 at 17:12
Hi Mark,
Interested in your comments on oil. I have an 80 series 1HDT and before that a 60 series 2H, both diesels. I used castrol RX 15W40 in the 2H and the motor is still in good condition, but the detergent based oil dirtied up very quickly. No oil usage though. I shifted to penrite 20w50 for the turbo diesel as I had been told that for the turbos the oil lost its lubricating ability on trials across the nullabor after about 3500 - 4000kms due to the degradation of the oil from the turbo. I would be interested in your comments about service intervals , the non turbo's will go for 10,000 and yet turbo's only 5000kms and what you would recommend in terms of oils and brands.


wet feet

FollowupID: 322837

Follow Up By: Member - Captain (WA) - Wednesday, Jun 02, 2004 at 20:51

Wednesday, Jun 02, 2004 at 20:51
Hi "wet feet"

A turbo engine is typically much harder on an engine oil due to the extra heat on the oil in the turbo bearings and also higher combustion pressures in the cylinders. This can lead to heat degradation of the oil and more blowby (particulates in the oil) from the higher combustion pressures.

A dirty looking oil is actually doing its job!!! The detergents are keeping the particulates in suspension and not letting them deposit on the engine internals. If you have clean looking diesel engine oil, where are all the particulates???

I am not sure what base oils are used in Castrol RX, but they are probably not synthetic (or even semi- synthetic). Typically, synthetic and semi-synthetic oils resist heat degredation better than ordinary oils. But most good brand name oils of the correct spec should last at least 5,000kms in a turbo engine without viscodity degradation.

Without a proper laboratory test report, I am not sure how one could tell an oil lost its lubricating properties and if no report is available, I would not pay too much attention to the rumour. Castrol is usually a very good oil and I have not heard this before.

As for your penrite 20W50, I am suprised Toyota recommend a 50W oil, not the more usual 15W40. As for what I recommend, there are many good oils on the market and I would stick with the big players or perhaps synforce (as advertised on explorOz). Their Cruiser oil is a semi synthetic and I have not heard any bad reports at all.

As for service intervals, I have always used 5,000km intervals on all the diesels I have had, 2 non-turbos and one turbo. It is the cheapest form of insurance one can buy. Longer service intervals on diesels should only be done where there is ancillary oil filtering (like a bypass filter) IMHO.


FollowupID: 322871

Reply By: Member - Bradley- Wednesday, Jun 02, 2004 at 22:46

Wednesday, Jun 02, 2004 at 22:46
The common consensus in the industry for diesels is not to go more than 2 grades up from what was reccommended originally. Yes going to ci4 in an older engine can clean out the deposits and cause oil consumption, but if the engine is in good nick then the rings can free up and stop the consumtion, but this can take 3 changes or more.. The soot loading and sludgeing is the main problem with the new motors and low sulphur diesel, along with the poor quality fuel we have here. Proper filters and changing are critical. We have an oil which completed an extended service test in europe - 100,000 k with filter changes etc. but in aus we can only give it 40,000 at best due to our poor fuel. Oils can break down with heavy use, but with most it is a case of you get what you pay for. Top qual oil is cheap insurance.
AnswerID: 61445

Reply By: Peter H - Saturday, Jun 05, 2004 at 00:02

Saturday, Jun 05, 2004 at 00:02
I run Mobil Delvac 1, fully synthetic oil, 10000 kms changes in a 100 series TD, I have just invested in an oil sampling kit and will send to the lab and see what comes back. I pay $46 for 5 litres but it is fully synthetic, 5W-40, it was a CH-4, now a CI-4.
AnswerID: 61779

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