Synthetic oil for diesel/transmissions

[jdoe71]

Have taken the advice from this board and am going to stop changing oil obsessively. But I think synthetic is a good idea. I used to use Mobil1 synthetic in my turbocharged race car and it was the only oil that could live under the heat so I know it's better than dino oil at least in that respect. But I know nothing about synthetics for diesels. I use RotellaT 15W-40 currently so I looked at RotellaT-SB (100% synthetic) today but it is a 0W-40 oil and that kind of scared me off since my engine manual calls for a 15W-40.

Anyone using synthetic oil in their sailboat diesel? If so what are you using or what have you used and didn't like? Same question applies to synthetic auto trans fluid for my Hurth transmission.

[never monday]

Ok, i gotta say it again. Save your money. I have 15 generators in a rental fleet here. They have never seen anything but regular old Valvoline. They had OE filters until the warranty ran out then went to Fram. The lowest total time unit is over 10,000 hours. I had a Yanmar industrial engine in a fork lift. It went 8500 hours moving forms around at a precast concrete plant. IMHO the cost difference of synthetic isn't justified in an engine below 200hp.
Above 200 were in a different ball game all together.

[Ex-Calif]

I hear the sounds of thundering footsteps (or at least fingerpounds - here comes Wheels.....

FWIW - I too think synthetics are overkill for periodic duty engines. Change your oil at 100 hours or 3-months whichever is shorter.

[Alan Wheeler]

My ears were twiching. Is someone talking synthetics????

Pat is right in some respects. The reason I am using a synthetic is for two reasons. It's a pig of a place to get at the sump bung and there is 11ltrs of oil to change. Yes there are benifits to synthetic, but unless you have a lot of reasons to use it than just simply the fact it last's a long time, it could be a little expensive to warrant.
The additional benifit to me that I have now since found is, reduced engine noise, reduced heat output. That was a biggy. My engine over heated if I opened it to full throttle. I have not measured fuel consumption as of yet.

[roverhi]

I wouldn't worry about the 0 in 0-40 viscosity. One of the beauties of synthetic is that it maintains it's viscosity over wide variations in heat range. Essentially, it does't thin out like dino oil as it heats up. 40 wt oil at operating temperature is like 0 wt. at ambient. Because of this greater loss of viscosity with temperature, Dino oil can't be made with as wide a vicosity range and still lubricate at the extremes of temperature. One of the reasons that they use it in Jet engines and reccomend for turbo's with their exrtreme temperatures.


The reason I favor synthetic is my boat, like most boats only gets periodic usage and I only use the engine to get out of the slip. It's a sailboat, dammit. Synthetics stand up better to that type of usage and don't crud-up as badly as dino oil from sitting. If I was using the engine regularly, dino would be the way to go. A three month oil change interval for me would be like changing the oil every 10-15 hours of use.

Aloha
Peter O.

[Boracay]

My understanding is that synthetic oils must not be used on a new (or reconditioned) engine until it has been broken in.

John Deere have supplied me with 30W oil for use during the first 10 hours.

[Jon D]

I switched to a semi synthetic a few yrs ago. Using Castrol Hypuron S 15-40. Engine is quieter, cooler etc. But we are full time cruisers so I put on a few hrs. It's an Perkins 4.236 with a big sump [12 qts] and a recommended change frequency of 250hrs [manual]. I know the synthetic is still good at that point from my motorcycle days. When I do a change it is dirty but that's it. Just was working on the engine yesterday [maintenance] and looked at the oil.. after 80 hrs just starting to get a little dirty.

I'm happy

[jdoe71]

Thanks for all the input. Pat I hear you, cost isn't really an issue since I was changing oil so often it's still going to be cheaper. Roverhi hit the nail on the head regarding my concerns, the engine sits all week, sometimes two weeks, then it gets some running on the weekends. Three weeks a year on holidays. We sail as much as we can, this year we didn't put 100 hours on the engine. Then it sits from Oct to early May in a cradle, with fresh oil in it of course. It now has 470 hours on it so should be broken in. P/O's were averaging less than 25 hours a year. This thing is more likely to die from lack of use than overuse, and I was hoping the synthetic might help with that. Oil must accumulate moisture from heat cycles, high humidity and winter storage and it seems synthetics are better able to deal with that.

Heat is also an issue at least for the trans as I read on this board heat is what kills most Hurth trans.

Anyone have any advice as to other specific brands that are good? I can't find Castrol synthetic diesel oil around here. I see brands like Amsoil, Royal Purple, Red Line, all they sell is synthetic but I have no experience with them.

[rtbates]

Originally Posted by Boracay

My understanding is that synthetic oils must not be used on a new (or reconditioned) engine until it has been broken in.

John Deere have supplied me with 30W oil for use during the first 10 hours.

That's 100% absolutely TRUE. Syn oil is too slick to provide the necessary friction to allow the rings, especially the oil ring to seat. And in the case of a forged piston, chromed ring turbo motor, wait at least 10K miles! I put Mobil 1 in my 300hp Miata's motor after 1k miles and she blew smoke under heavy boost. Back to dino for an additional 9k or so miles and all is swell.

It's also this inherent lack of friction that makes it a bad choice for older engines. If placed in a older motor you'll most likely develop leaks that were never there before. All this is based on experience.

[never monday]

Originally Posted by jdope71

This thing is more likely to die from lack of use than overuse, and I was hoping the synthetic might help with that.

This is exactly where I think synthetic is a disadvantage.
Synthetic is so slippery that further wear is negated. Well in a engine that is hardly used, cylinder wall glazing is a real concern. If you stay with Dino oil you'll get the benefit of wear that will aid in the longevity of the engine. Yes, I said wear is good.
Most of the engine "failures" I see are from lack of use. It's a term I'm coining as lazy engine syndrome.
The engine is started at the dock and allowed to idle to warm up for 5-10 min. then it motors out of the no wake zone at low to medium load and is shut down to sail. Now when were done for the day or weekend we do the exact reverse. The whole time we think we're being kind and loving to our iron wind. Well, get over it. Beat that thing like the worst rugrat you've ever had. It will love you more and live longer.

Long live simplicity, diesel and dino oil.

Take a look at this guy, I agree with him. I've killed the compression in an engine in my youth from going synthetic too soon.
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

[S/V Antares]

Hello Pat, I think you are spot on the money. The rugrat analogy works well.

I think we worked together when I was selling Little yellow Diesels for that Dutch company. Glad you are in the fourm.

Will Heyer

[jdoe71]

Pat, that article pretty much describes how we broke in the race engines. Put in low quality dino oil, warm it up, then do about 5 passes full throttle through 2nd to 5th gear up to about 500 rpm below redline and back down through the gears downshifting from 5th to 2nd letting the compression slow the car. After that, drain the dino juice, put in the synthetic and race. We had zero engine failures doing this routine. These were long races up to 24 hours flat out, never less than 4 hours, we put about 200 hours on an engine before teardown and rebuild, wear was minimal on everything and I swear we could have easily gone double that number of hours. These were production based engines and we were pushing them pretty hard with lots of boost.

Some days the wind is on the nose, then we motor for hours. With jobs and schedules to keep, that's just a reality, at least for now. Jeez that dino juice looks thin after 4 or 5 hours of motoring at cruise speed. Guess I'm trying to find a balance and that's hard to do when the conditions vary so much. I try to always run the engine long enough and under enough load to get it up to 180 degrees before shutting down.

Also leaking gaskets is a concern, I found that in street driven cars that were not brand new synthetic would causes leaky gaskets and the leaks stopped when dino was put back in.

Maybe best to stick with the RotellaT or some other good quality dino. What about synthetic in the trans?

[never monday]

Originally Posted by S/V Antares

Hello Pat, I think you are spot on the money. The rugrat analogy works well.

I think we worked together when I was selling Little yellow Diesels for that Dutch company. Glad you are in the fourm.

Will Heyer

Will,
Good to see you here. How have things been going? What are you doing these days?

Guys this guy has probably forgotten more that I Know about diesels and that Yellow one in particular.

I've never run synthetic in a trans. But, by the design of the Yanmar Kanzaki trans I would strongly advise against it. That box only transmits power thru friction. Add an oil with less friction and you get less power output.

[jdoe71]

I have a Hurth HBW-50 2:1 ratio. Spec oil is Dexron II ATF. I haven't been able to find any yes or no to synthetic in the manual or on the mfg website. ZF took over Hurth and I can't find any data on older transmissions on their website.

The only cautionary thing in the manual is this:
WARNING: ADDITIVES SUCH AS MOYBDENUM SULPHITE OR THE LIKE MUST NOT BE CONTAINED IN THE OIL UNDER ANY CIRCUMSTANCES.

Does that warning sound like synthetic is not OK in this trans? My concern here is minimizing heat.

[S/V Antares]

Hello Pat! I have been working in Marine Audio for a few years since I left my Dutch Friends. Nice break. I am retiring in Nov. and headed south for the winter. No plans after that.

I can see some issues with the Synthetic in the gearbox. Too bad as they need to run cooler as a rule, to last.

Hey, You are a truly inventive guy. Why don't you gin up a trans cooler for the hurth/ZF mechanical gears. The position of the fill and drain being on top of each other should make it easy. You will need a way to pump the oils as thes boxes are splashers. There was a water box for the side oposite the shift mechenism but it was just a heat sink for the case.

Perhaps a bigger heat sink?

Keep in touch!
Will Heyer

You going to get out to the salt water someday