API Engine Oil Ratings

[rScotty]

Can someone enlighten me on API oil certifications?

I'm trying to decide how to view the Kubota spec in my owner's manual. For the M59 it says that CJ-4 type oil is specifically not allowed because of the filter type on the M59...and it says CF-4, CG-4 and CH-4 cannot be used in engines with external EGR valves - which the M59 does have. That only leaves as allowable diesel engine oils that are CF or CI-4.

Here's what is confusing me... If an oil meets CI-4 but also the other ratings then which one dominates? My favorite is Shell Rotella T - which meets all of the required ratings but also meets all the ratings which are not allowed! Searching around, I have found that there are some oils with a narrower rating range - for example one which will meet CI-4 without also meeting CJ-4, but those types of oils are not easily found. It's possible that they just didn't test it for CJ-4 compliance... So I'm not sure whether an oil that meets CI-4 but also has the other ratings qualifies or not. ?

Does anyone know a petroleum API specialist who could answer these questions? Or does anyone have a copy of the engineering requirements behind the API ratings and I'll try to figure it out myself if. Hmmm....I'm guessing API provides the technical requirements for the different ratings to someone. I'll ask....
Thanks, rScotty

 

[Chuck K.]

That is a very good question Scotty, I put Shell Rotella-T in mine, I thought it meet or exceeded all diesel manufacture's specs. All the crazy different ratings can bumfuzzle you when searchig for the correct oil.. I suppose this could lead to a similar debate SUDT vs UDT?

Actually this really, really irks me, will we have to use kubota's top secret proprietary SAE/API/ISO-9003, C4/rX6-S21a, special formulated oil blended only for the M59? And OF course it will only be available from selected kubtota dealers... Man dont get me started...

 

[jmac1970]

The API CF rated oil now is classified for diesel powered cars and light duty trucks. Kubota recently changed their oil recommendations to a CH-4 or higher quality oil in their engines, because the engines are medium to heavy deisel powered, wouldnt you agree?

 

[medicshawn]

I sent an Email to Kubota to see what they say.

 

[rScotty]

The API CF rated oil now is classified for diesel powered cars and light duty trucks. Kubota recently changed their oil recommendations to a CH-4 or higher quality oil in their engines, because the engines are medium to heavy deisel powered, wouldnt you agree?

That might be true, but maybe not deep enough. According to how I read API's info, the basic CF oil standard was set up without emissions being an issue. The issue was quality lubrication, and the CF standard was restricted to off-road vehicles - like tractors. The CF standard allowed high sulphur fuels. CF oil is still OK for the M59 according to Kubota.

Hmmm....
CH-4 is a newer standard, but doesn't seem to be a higher quality oil, but rather a modification to meet 1998 emission standards for low sulphur fuels. That makes me wonder if the driving forces there is oil quality or politics.
CI-4 happened next, and it modifies the oil standard to keep the quality of the oil up when exhaust gas recirculation (EGR) is part of the engine design. Our M59s are EGR type....that's part of the new generation diesel emission engine in the M59.....although from a strictly wear standpoint it may not be an advantage.
CI-4 was the design standard used by Kubota when they originally designed the engine and is recommended now.
Apparently Kubota was aware of the newer standard called CJ-4 which modifies the oil so that particulates from the fuel and engine oil can be either filtered or burned out by a special muffler. There must have been something about the CJ-4 type oils which Kubota's engineers didn't care for because there is a specific warning in my operator's manual against using the new CJ-4 oils.

It will be interesting to hear what Kubota says if they ring in on this. Being an old engineer myself, I gotta keep remembering to bring my grain of salt as there are political sides to most standards these days - but then frankly there always were. Then it would come down to whether to side with the engineers who designed the motor or the oil companies who sell oil for it.
Like a lot of things it comes down to getting as many "facts" as one can and then make the call for yourself. To my way of thinking that's the strength of the internet. I've no problem with buying Kubota's own compounded oil if that's what it takes. But I'd like to see some proof.
rScotty

 

[jmac1970]

The CJ-4 was delevoped by API to handle the EGR and ULSD issues. You will have plugging and clogging problems in your filters with the old types of oil. I would use a fuel treatment as well.

 

[WH401]

The reasons I wouldn't use CJ-4 oil are because:

1. Older CI-4+ oil was designed around the use of Low Sulfur Diesel fuel ( LSD, 500 ppm), and because of this it had a higher TBN to control the high acidity level that was accumulated from the use of a high sulfur fuel. When CJ-4 was designed, they based it around the use of Ultra Low Sulfur Diesel fuel (ULSD, only 15ppm), because this was one of the only few key ways to obtain the emissions standards needed from newer diesel engines. The problem is that if you run CJ-4 oil in an engine that is being powered by diesel fuel that has a PPM rating of 15 or higher, than your oil will break down much, much faster because it can handle the high acid amounts produced from the fuel. Another reason why the lowered TBN of CJ-4 oil is bad is because the higher EGR rate of the emissions diesel engines will introduce more nitric acids into the oil which the lowered TBN will not be able to combat. Running CJ-4 oil in an emissions compliant diesel engine is your only option as running CI-4 oil will cause your diesel particulate filters (DPF) to plug. Plus the additive packages in CI-4+ will cause damage to your DPF's, but that's not a worry in a pre-emissions diesel engine.

2. CJ-4 oil's have a reduced level of the additive ZDDP, which is basically zinc and phosphorus. These two parts control the amount of wear that is put on moving parts, especially camshafts. Why did they lower this?, because it causes damage to the DPF and EGR's.

If you have an engine that has a DPF on it, or is emissions compliant, than your only choice is CJ-4 oil. But if you have a pre-emissions engine, I would stick with CI-4+ oil, and not take the risk with the new CJ-4 junk. You have lots of options out there for CI-4+ oil. John Deere's "50" brand oil is a dino 15w-40 oil rated at CI-4+, Amsoil has two fully synthetic diesel oils at CI-4+, Valvoline makes Premium Blue Classic which is a dino 15w-40 oil rated at CI-4+, and I've heard recently that Shell was coming back on the market with a CI-4+ version of there dino 15w-40 Rotella-T oil.

 

[jmac1970]

Thats why I use Schaeffer synthetic in all my engines, it takes care of all the issues.

 

[WH401]

Thats why I use Schaeffer synthetic in all my engines, it takes care of all the issues.

Which one, exactly?

 

[rScotty]

The CJ-4 was delevoped by API to handle the EGR and ULSD issues. You will have plugging and clogging problems in your filters with the old types of oil. I would use a fuel treatment as well.

Not sure which issues you are meaning here. The way I read the synopsis on the CJ-4 specs it seems that CJ-4 refers to oil chemistry changes to make the burnt oil more compatible with exhaust particulate catalytic converters. It doesn't have anything to do with engine oil filters.
rScotty