Diesel oils-an interesting topic/selection!

Basecamp,

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!

Cheers
Muzza

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.

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.

regards,

wet feet

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.

Cheers

Captain