Oil formulation - American vs Japanese

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I recently came across this post on another site and have also read the post on this site re Ca, Mg and TBN. Being the owner of a Japanese manufactured diesel vehicle, I am interested to hear the opinions of those a lot more knowledgeable than I am.

'The oil sold in Japan typically has calcium based detergents in it at levels of 3000-4500+ppm (parts per million) this is a very detergent oil compared to a lot of oils formulated for American engines (700-2500+ppm) magnesium based detergents, magnesium based detergent is thermally unstable at normal working temps of a Japanese diesel engine that is why it is not used in Japanese OEM oils) as a side benefit extreme levels of calcium have a very strong bearing pacifying affect reducing the bearings susceptibility to chemical attack by its own oil which contributes to the onset of subsurface fatigue failures. Synthetic oil per-se is not a fix (or prevention method) you want oil with low or no magnesium and preferably in excess of 3000+ppm calcium based detergents. The oils that I know of that meet the above requirements are: Caltex Delo CXJ 15w40 (the J is for japanese) mineral oil, Castrol J-Max 15w40 mineral oil, Amsoil Marine oil 15w40 synthetic oil, Amsoil series 3000 5w30 synthetic oil, I know BP in Europe makes some nice high calcium synthetic diesel oils also but I don't know names or product codes'.
 
Interesting. I do prefer oils to have a calcium add pack, vs magnesium. I hear magnesium is "rougher" on the engine that calcium.
 
Frot,
I think I'm reading the reference to the investigation that some people did into the Toyota Land Cruiser 1HDT bearing failures that were occurring in the 90s.

If my supposition is right, that was a very good read, and quite detailed and believable.

Was the reason that I used Delo CXJ in my Navara for the period between 2,500km, and 10,000km (two changes) before going synthetic at 10,000km.

CXJ is unobtainium these days I think.

Had the following as an attachment that explained the design differences between the Japanese, American, and European diesels, and why Caltex had three strains of engine oil for them

1HD-T_pg1-caltex.jpg


1HD-T_pg2-caltex.jpg


1HD-T_pg3-caltex.jpg


1HD-T_pg4-caltex.jpg


What Japanese diesel are you driving ?
 
Originally Posted By: Shannow
I think that Toyota spec a 5W30 for those don't they ?


On the Mobil au site they recommend 5W40 Delvac M1, or Delvac MX 15W40 - we use MX 15W40 in them. They will die from a cooling system related issue before any oil problem rears it's head. cook them and the head will crack, nearly every radiator is 80% blocked, get it rod cleaned.
 
I have attached a page from the Toyota Owners Handbook showing the oil they recommend. I have also come across another article and have pasted the contents of a couple of paragraphs at the end of this post - never a shortage of opinions!

Can't find a way to upload the document but basically the hand book recommends 20W-50, 15W-40, 10W30 and 5W-30 (preferred) based on expected temperature range.

Extract from technical article:
'Multi viscosity oils are one of the great improvements in oils, but they should be chosen wisely. Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter. In the winter base your decision on the lowest temperature you will encounter, in the summer, the highest temperature you expect. The polymers can shear and burn forming deposits that can cause ring sticking and other problems. 10W-40 and 5W-30 require a lot of polymers (synthetics excluded) to achieve that range. This has caused problems in diesel engines, but fewer polymers are better for all engines. The wide viscosity range oils, in general, are more prone to viscosity and thermal breakdown due to the high polymer content. It is the oil that lubricates, not the additives. Oils that can do their job with the fewest additives are the best.

Very few manufactures recommend 10W-40 any more, and some threaten to void warranties if it is used. It was not included in this article for that reason. 20W-50 is the same 30 point spread, but because it starts with a heavier base it requires less viscosity index improvers (polymers) to do the job. AMSOIL can formulate their 10W-30 and 15W-40 with no viscosity index improvers but uses some in the 10W-40 and 5W-30. Mobil 1 uses no viscosity improvers in their 5W-30, and I assume the new 10W-30. Follow your manufacturer’s recommendations as to which weights are appropriate for your vehicle.

Viscosity Index is an empirical number indicating the rate of change in viscosity of an oil within a given temperature range. Higher numbers indicate a low change, lower numbers indicate a relatively large change. The higher the number the better. This is one major property of an oil that keeps your bearings happy. These numbers can only be compared within a viscosity range. It is not an indication of how well the oil resists thermal breakdown'.


If it is preferable to use an oil with the lowest 'spread' between the first and second VI number I have to ask why Toyota would recommend the 5W30 as their preferred oil even though I am driving my vehicle in Queensland where temperatures below zero deg celsius are rare but temperatures in excess of 35 deg celsius are not uncommon.

Out of interest my local Toyota dealer uses Valvoline Synpower 5W30, yet the Valvoline technical advisor I spoke to on the phone suggested that Valvoline Super Diesel 15W40 should be used in my vehicle and not the 5W30 Synpower.
 
I think I had a brain [censored] on my last post. What I meant to ask is if a higher VI is better (at least in a hotter climate) then why is the 5W30 preferred by Toyota. One can hardly say that temperatures across NZ and Australia don't vary much!
 
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