I have two 4WD vehicles with diesel engines, in the summers the temperature here in India exceeds 50c in some parts so I have been using CD/CF rated SAE40 oil, in the winters the temp can drop to 0c where I live and therefore I have been using CF rated 15W/40 oil.

Now there are newer oils in the market rated CH and CI and my question is that is there any gain in switching to these oils, my average drain interval is 6000Km.

One vehicle has a MB OM 616 turbo and other is a HINO 4009cc W04D diesel.

I don't know much about diesel oils, but I was under the impression that CF is not one of the higher ratings for diesel oil. Some of the ratings I believe are more stringent are CF-4 through CI-4 (EGR engines). But first you need to look at your owner's manuals for what the manufacturer specifys. Also, with the high temperatures you indicate, maybe you should look at a synthetic diesel engine oil.

Hi,

I am sorry but I meant CF-4 and CI-4 rated oil. Many thanks for your reply.

Well, at least here in North America, the modern CH-4 and CI-4 oils are very good, much superior to the CD rated oils common many years ago. Besides better additive packages, the modern 15W40's typically have better quality basestock (example would be Penzoil Long Life, which is entirely Group II).

Typically the big names in diesel oil here are Mobil's Delvac 1300S, Shell's Rotella T, Chevron's Delo 400, and Pennzoil's Long Life...all of which sell for about $5/gallon. What oils do you have avalible? Prices?

Hi Abus,

All the oils you mention in your list are avaialble here in India and additionaly you can also acquire the ones made by Indian companies which are also quite decent. As a matter of fact, the only CI-4 rated oil launched here is from Bharat Petroleum, a local company.

The reason I asked this question is because as per the SAE chart and MB chart, SAE 40 is the safest way to go if the ambient outside temps are over 40c and yet there are hardly anything over CF-4 rating for single weight oil. I lived in NY for 17 years and followed the same procedure for summers on my diesel vehciles, for my gasoline vehciles I had nothing to worry about as I only used Mobil-I. For winters I dont mind using multi grade 15W-40 oils, but it is the 50c summers in certain parts of India that makes me real paranoid about using anything less than SAE40.

Same goes for tranny fluid, I prefer using 85W-140 as it gives me total peace of mind because of its all weather rating, yet there are very few companies here marketing this grade here in India as well as in the US.

Well, remember that the actual oil film thickness should be the same with 15W40 and straight 40 at high temperatures. Overall, I think it is safe to say that straight 40 weight oils here in NA tend to be crappy Group I basestock oils...mostly brand "X" oils...I would much rather have ANY of the reputable 15W40's than an off brand 40 weight.


In general, Delo and Delvac are nearly the same in performance...Rotella lacks some of the cold weather properties as delo/delvac, and Pennzoil is a relative newcomer...the high ,oly content of Long Life seems to help oil consumption.


If I were in a tropical climate, I would probably run Long Life...though I doubt you'd see a major difference in wear metals with any of the major 15W40's.

The irony is that if one were to go by the oil pressure gauge, SAE chart and general seat of the pants then experience shows that unless it is Delvac I, all other multi grade oils have a tendency to thin when the going gets really hot so at ambient temps above 40c, I would say it is safer to use SAE40 unless one can afford the super expensive Delvac-I. However in winters where the temps here drop to 0c I would only use 15W-40.

Do you have an oil temp gauge? I would imagine that a straight 40 would be a good bit thicker under 100c...but should be in the same visosity range at 100c. Also, if the 40 is a kinda cheap oil, it might thicken out of grade in that kind of heat. I don't have much experence with it, but some aircooled applications show improved cylinder wall wear levels on the very high quality straight weights, but otherwise, straight weights are nearly unheard of in modern applications here.

Personally, if you can get oil analysis done cheap, I'd check that and see if the straight 40 is staying in grade, and compare wear metals between it and one or another of the 15W40's (my preference in Long Life, for the Moly). Here in the US, Mobil is selling rebottled Delvac 1 for ~$4.50/qt as Mobil 1 "Truck and SUV"...if you have that avalible, I'd run it, and extend the drains. Even without oil analysis, I would feel comfortable extending drains out with Delvac 1 to at least double what you're running a conventional, Group I straight 40 at.

Abus,

Oil temp gauge is what I have always wanted in my vehciles, especially the ones with turbo engines but sadly most modern manufacturers omit this important gauge.

I use Delvac 1340 SAE 40 oil so dont think that is in the lower quality cateogory of oils, it is that I find that under severe heat, the single weight oil holds up much better, long time back MBZ engineers came to the same conclusion and therefore in their reccomended list of oils for OM616/617 engines they specify SAE40 for ambient temps of over 30C.

BTWelvac-I is US$15 a gallon here and way out of my range.

Delvac 1340 is a good oil...perhaps it, and the other heavy duty straight weights (Delo/Rotella, etc) are more common in your area? Like I said before, the better makes of heavy duty straight weight oils are not commonly avalible in North America, so it is odd to think of buying Delvac 1340 over the counter!

If Delvac 1 sells for less than $4/qt (US), what does Delvac 1340 sell for?

For comparision, over the counter price on Delvac 1300S here is about $15-17 in the 2.5 gallon container.

Finally, although I am not familar with the MBZ requirement that you mention, I wonder how long ago "a long time back" was? I would say that the major 15W40's are radically superior to their counterparts of 20 or even 10 years ago. I would be suprised if the wear metals would be significantly different in most light vehicals between, say Delvac 1340 and Delvac 1300S at high temps.

5 gallons or a 20 liter of Delvac 1340 sells for around US$35 here.

The test was done by MBZ in the early nineties as they were curios on the effectiveness of multi grade oils.

Hi there,

As a Lubricant specialist my choice of oil will not depend ONLY on SAE number, 30, 40 or what ever. All the SAE number defines is the viscosity of the oil.

Over the past decade Engines oilS have become multigrades. All this means, the oil can possess the viscosity of a range of SAE numbers, 20w/40 etc..

Current trends show that a lower viscosity oil 5w 10w and so on have reduced energy consumption. They are also pumpable at fairly low temperatures.

The crux of the matter is to choose the oil (petrol or diesel) with the highest performance. API has issued a coding/nomenclature for a series of performance related tests. At the initial stages the SA and CA (for petrol and Diesel) were straight minerial oils with little or no additive package. Today we have SH and CI4 type of oils that belong to the top rung in performance.

Incidently, the makeup of the new generation of oils take into considerations the viscosity (SAE number) of the oils. If I were in a cold place like Canada I would rather opt for 0w/xx and 5w/xx or 10w/xx for the rest of the world.

Hussam Adeni

Good point. If I ever use a 5wxx or 0wxx you can bet I will be using synthetic. A 10wxx synthetic might be enough cold temp performance for southern Ontario though. Also can get an oil pan heater. For the rest of the world 10w30, 15w40. I ran 10w40 last winter with temps down to 0F (-18C) but had the oil pan heater so only had unheated starts down to about 10F (-12C). Performed fine. I will be running 15w40 this summer, but only to maintain spec oil pressure. My other two vehicles run 10w30 year round.

The SL specification is pretty weak, I prefere to look for the various manufactuer approvals, in combination with spec sheets and oil analysis to pinpoint oil performance.

In an extremely hot enviroment, it is hard to fault an extremely high rated straight weight oil like Delvac 1340...the fuel economy loss would be pretty trivial.

quote:

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Originally posted by Abus:
The SL specification is pretty weak, I prefere to look for the various manufactuer approvals, in combination with spec sheets and oil analysis to pinpoint oil performance.

In an extremely hot enviroment, it is hard to fault an extremely high rated straight weight oil like Delvac 1340...the fuel economy loss would be pretty trivial.

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Having used premium high quality CH-4 rated multi grade oil in the summer, my experience is that apart from Mobil-I and Delvac-I no other oil retains its thickness like a good quality single weight oil like Delvac 1340, Valvoline All Fleet, Gulf SDMO, Castrol CRD 40 extra etc. This is in extreme 50c weather, for winters the CH-4 and higher rated muti grades work out pretty well.

Gurkha,

I suggest to use CH4 oils in your vehicle.
Note that CH4 oils contains Group II base
stock,which has excellent thermal and oxidation
stability.SAE 40 straight wt oils may have
group I base stock,which eventually forms coke
deposits in turbocharger,combustion chamber,
piston grooves and land areas.Oil aanalysis
will not identify these deposits.Over a period
of time deposits grows,shortens engine life.
You can estimate these deposits during teardown
inspection of engines.

CH4 oils keeps your engines free of deposits.
(Ensure that Group II base stock is used)
BTW,Lubricant cost is insignifficant relative
to total maintenance cost.

Regards
CVB.

I'm pretty sure that the newer straight grades like Delvac 1640 use as good of basestocks as the average 15W40 (only Pennzoil Long Life is completely Group II, I'm pretty sure that CH-4 Delo and Delvac have some Group I, not sure about the CI-4 versions)


BTW, In gas engine in that hot of a climate, I think I would run Mobll 1 15W50 in preference to straight grades. If Delvac 1 is well under $5/qt, I would imagine that they practically give the 15W50 away.

I fully agree with Abus, if price were no object, I would use Mobil-I in my gas engines and Delvac-I in my diesels. As a matter of fact I still have a 526,000 milles Honda Accord V6 running as good as new due to my only and extensive use of Mobil-I in engine and tranny, but this was in US where Mobil-I though pricier than others, is still affordable unlike here in India where it is priced beyond a sane range. Same goes for Delvac-I.

I agree with Balu on the CH-4 oil being a superior product especially on long runs, but the problem is that if the outside ambient temps are hitting on 45c+, no multi grade I have used so far apart from Delvac-I retains its stabillity and viscocity, one hard run in hot 50c weather and you see the oil pressure drop and the oil thin out on the dipstick. The SAE 40 with CF-4 rating at least gives you a level of protection and as long it is drained in under 5000km interval, coking shouldnt be a problem.

The same goes for tranny oils, my MBZ engined vehcile uses ZF tranny which only calls for ATF but sadly dino ATF thins out in matter of months leaving the gears in virtual metal to metal mesh.

Same thing happens to my other vehicle where the regular GL-4 SAE 140 used in summers is turned to water due to extreme gear box load, only the pricier synthetic gear oils can survive the onslaught but sadly synthetic ATF and gear oils are yet to be marketed here in India.

In the end all I would say is that visccocity breakdown as well as thermal stability is something hard to ingone in mineral based oils and it is better to be safe than sorry if one is dealing with temperature extremes.

Sorry for my long post.

Gurkha,

Viscosity drop is due to VI shear thinning,
Thermal cracking,Fuel dilution,Wrong oil added.
Increase in viscosity is due to oxidation,
Evaporation loss,Soot contamination,wrong oil
added.You observed viscosity drop in CH4 oils,
signalling that there is no oxidation.SAE40 oil
retains its viscosity,may be oxidation is
occuring,which is offsetting the viscosity drop.
Viscosity is not the only factor to judge the
oil performance.You need to get Spectrometric and Ferrographic analysis for identifying engine
condition and contaminant condition,FTIR analysis for oil condition.

Pls note that during load transients certain oil
losses its hydrodynamic property,when load is
released,viscosity retains.Unfortunately K.viscosity will not identify this failure mode.

Regards

Bala.

Bala said: "Pls note that during load transients certain oil losses its hydrodynamic property,when load is released,viscosity retains. Unfortunately K.viscosity will not identify this failure mode."

I believe you are talking about temporary viscosity sheer, which I understand was a problem of early viscosity index improver polymers where the polymers under high stress, such as in the main bearings, would nest like spoons, and cause a viscosity drop. This was overcome as oil tech improved; however, later it was found to be an energy saving measure and was applied to help some oils meet the necessary criteria to be labeled with the words "Energy Conserving." So avoid those words in the API donut on the oil bottle. What you want is an oil with a good HTHS (high temp high sheer) viscosity. Usually HTHS improves with increasing oil weight and/or by using synthetic. Oil company product data sheets sometimes list HTHS values. Typical 10w30 passenger car motor oil would HTHS around 3.3 cSt @150C. Diesel motor oils typically are into the 4.0 and up.