Castrol and Rotella Diesel

[pamcopete]

This is a reprint of a post that member skidro made in another thread. It is reprinted here as there is a lot of interest and discussion about using Diesel oil in a motorcycle engine.


After reading this discussion and several others I saw little to no info on the Castrol Diesel so I wanted to get an opinion.

I have also written to Castrol asking for ZDDP ppm information. I will post it if they write back.

Just in from Castrol Oil: Not encouraging

Although Castrol Diesel oils carry an S rating, its primary credentials are diesel. The S rating is meant for short term use if the owner cannot find the appropriate gasoline engine oil. Diesel engines and gasoline engines have different operating regimes (loads, temperatures, speeds, fuel, exhaust recirculation); the lubricants are formulated differently (additives, ZDDP) to be in line with the primary operating requirements of the engine. Diesel engine oil is formulated with very high levels of detergency to counteract the soot that is circulated back into the oil. Detergency is surface active and does compete with ZDDP for the surface of the cam lobe and lifter face. The proper engine oil to use long-term in gasoline classic car engines is an oil designed for use in a gasoline engine with the correct level of ZDDP to protect his cam and lifters.

Product Recommendations for Flat Tappet (Solid Lifter) Cam Engines:

Castrol Syntec SAE 20w-50 (Recent reformulation identified by "Recommended for Classic Cars" text on back label) (min Zn = 0.12 = 1200 ppm)(full synthetic)

Castrol Consumer Relations

[pamcopete]

Virtually all modern multi-weight oils are detergent oils. Detergent oil, cleans the soot of the internal engine parts and suspends the soot particles in the oil. The particles are too small to be trapped by the oil filter and stay in the oil until you change it. These particles are what makes the oil turn darker. These tiny particles do not harm your engine. When the oil becomes saturated with soot particles and is unable to suspend any more, the particles remain on the engine parts. Fortunately, with the current oil change intervals the oil is changed long before the oil is saturated.


My comments:
So, apparently, you do not need the very high levels of detergent in a Diesel oil for your motorcycle, and the detergent impedes the action of ZDDP, which you do need.

[islanddave]

Very interesting Pete, i am very much enjoying what information we have all found on different oils. I myself am still sitting on the fence about what to use. It may come down to a motorcycle specific oil such as Castrol 20w 50 Grand Prix, and then add a ZDDP additive such as this to the mix. Also reading the information they have regarding the uses of racing oil, diesel oils, makes me rethink this whole thing entirely. In particular look at the analysis of this stuff to show the zinc and phosphorous content. Looks good to me.

www.zddplus.com/

Dave

[pamcopete]

islanddave,

It was our member skidro who wrote to Castrol to get that information on their Diesel.

I believe that too much ZDDP in the oil can cause clutch slippage, so the usual too much of a good thing. About 1,000 ppm is adequate. Read the post on Pennzoil as well, because that info came from Pennzoil themselves.

[islanddave]

Do you really think that 1000ppm is enough? I've read somewhere that 1200PPM is the bare minimum with flat tappets and that high lift cams required more about 1400-1600. Too much ZDDP will cause pitting in metal so I guess anything above 1800. My engine is about 700cc has a web cam and the accompanying high tension valve springs. I just wanna make sure my engine doesn't wear out before its time. If the ZDDP would cause clutch slippage then I gues I would re-drain and refill with less ZDDP and hope that it would go away.

Dave

[pamcopete]

Just to add to the confusion, this from Shell regarding Rotella in motorcycle engines:

Can heavy-duty diesel oil be used in motorcycles?


Motorcycle gasoline engines may not seem in the same league as the big displacement diesel engine under your hood, but they share some of the same lubrication requirements. So yes, in many cases, a premium heavy-duty universal oil capable of serving both diesel and gasoline engines is the best choice for your bike.

The high power-to-displacement ratio of a motorcycle engine means rod and main bearings are subjected to loads that are not normally found in passenger car engines. The valve train is also highly loaded, and requires extreme pressure boundary lubrication. The same can be said about gears in the transmission, which are normally lubricated by engine oil. Oil additives containing phosphorus protect these highly loaded extreme pressure areas (in both gasoline and diesel engines). Because diesel engines have higher loading of components, more of the phosphorus-containing additive is present than in typical passenger car oils. And with advanced catalyst systems for gasoline engines, the phosphorus content has been declining in passenger car oils.

Since many bike engines are air-cooled, and tend to be operated at high power outputs and speeds, their lubricating oil needs to be more resistant to high temperature oxidation. That?s another advantage of a premium universal oil. Another thing you want in your motorcycle is oil that has excellent viscosity control, so that with use it retains high temperature viscosity. Some multiviscosity grade passenger car oils, subjected to extreme loads, can quickly thin out. Their viscosity can drop to the next lower grade.

One last thing to consider is whether oil contains friction modifier additives. For improved fuel economy, most passenger car oils have such an additive. But the wet clutch in your bike doesn?t perform right with friction modifiers. Universal engine oils don?t have friction modifiers.

Be careful choosing diesel oils. Not all of them are universal. In addition to the API Service Category CI-4 PLUS for diesels, look for API Service Category SL.

Premium universal oils like Shell ROTELLA T Multigrade are formulated for heavy-duty performance, and your bike engine has some heavy-duty challenges for oil. For optimum performance, be sure your oil is up to the challenge.

[Burns]

Round and round we go and Rotella (which many XS folk in the know have run for years, and swear by) stays in the running as the oil of choice.

And it is cheap.

Glad Shell cleared up the detergent issue, and thanks to all for this most informative thread

[pamcopete]

Burns,

Well, there was no mention of detergent in the above article from Shell, so the jury is still out on that question. Shell also describes its Rotella as a 'Universal" oil, formulated for both Diesel and gas engines and they caution you to remember that not all Diesel oils are Universal.

[pamcopete]

More feedback from Shell Rotella:

Rotella T Triple Protection 15W-40 and Rotella T6 Synthetic 5W-40
both pass the JASO MA wet clutch test for motorcycles. Thank you for your interest in Shell products. Richard Moore

[Burns]

I read

"Be careful choosing diesel oils. Not all of them are universal. In addition to the API Service Category CI-4 PLUS for diesels, look for API Service Category SL.

Premium universal oils like Shell ROTELLA T Multigrade are formulated for heavy-duty performance, and your bike engine has some heavy-duty challenges for oil. For optimum performance, be sure your oil is up to the challenge."

to mean that the Rotella was a "universal" oil suitable for motorcycles, which was my original concern for this particular "diesel" oil.

It cleared up the issue for me, if my reading is correct, some diesel oils may not be suitable but the Rotella is.

[pamcopete]

Burns,

Well, the issue that bothers me lately is that all new diesel engined trucks have a catalytic converter, and I assume that means that diesel oil will have to reduce its ZDDP content, and that an oil that advertises itself as a "Universal" oil should work with vehicles that have a catalytic converter, meaning that their ZDDP content will be reduced. Motorcycle specific oil still has the higher levels of ZDDP, and I'm beginning to think that that is the only oil out there that has a higher ZDDP content, so I am leery of "Universal" oil.

I was happy with my PennZoil 20W50 automobile oil for 14 years, but when I saw that they had reduced the ZDDP, I switched to PennZoil Motorcycle oil, 20W50 which has the higher ZDDP content.

[Burns]

well, there's a classic example of knowledge breeding confusion. I had no idea that they were putting cats on diesils. I would have thought the soot would render them useless in no time.

I'm thinking there was some cherry picking in the oil test - you know publishing the results of only the oils that the sponsor could beat. Rotella and Mobile 1 were conspicuously absent

[pamcopete]

Burns,

This from WikiPedia on the subject:

In the United States, all on-road heavy-duty vehicles powered by diesel and built after 1 January 2007 must be equipped with a catalytic converter and a diesel particulate filter.[6]

Just Google "diesel catalytic converter" and get up to date.

[grizld1]

Here's a little experience to dispel the confusion, Burns. When my old engine went from bike to bench in favor of the new mill (I do one every few years just to try new things), it had been run around 20K miles on Rotella T 15W/40 changed every 1K miles, the last 4K or so with 2 oz./gal. of ZDDPlus; VOA's on the current Rotella T formula show around 1050-1100 PPM phosphorus, which is used as an indirect measure of ZDDP content. My micrometer showed no measurable wear on the Shell #1 cam, the rockers had a very nice glassy finish, and the valve stem tops and OEM adjusters were in very fine condition--valve lash readings with a dial indicator confirmed the settings made with feeler gauges to the limit of measurement. Even with the breathed-on motor (700 cc., CR>10:1, cam as above, port work, VM36 carbs, etc.), there was no clutch slipping. That having been said, I'm using Spectro 4 20W/50 in the new engine as a hot weather oil and like it a bit better.

[Burns]

Sounds like the Rotella did a great job in your " real world" data Griz. "No measureable wear" is hard to beat. It will be interesting to see how the Spectro does when you get another 20 on the new motor and decide to experiment with fuel injected heads or something.