Oil

Which grade of rotella weight should I be using for my ford lelham 120 hp Diesel engine ?

According to many of the well respected/well known Ford Lehman Guru's you cant go wrong with Rotella mono grade 40 (getting a bit harder to find these days!) due to more modern diesels running multi grades and synthetics but these engines are designed for such,

Our lovely old Ford's were designed in the days of mono grades and have successfully run on these for numerous years with no issues as long as regular changes with filters are done on schedule, for me it's 250 hours!

Now wait for it!!!

Cheers Steve

Forgot to say dont forget to change your injector pump oil @ 50 hours if you have the original Simms pump, same oil as the engine,

Now back to the engine oil some Lehman manuals say SAE 3O again mono grade , but many others say SAE 40 if over 90F operating climate, but the bottom line for many engineers is that as these engines are getting on a bit, so using 40 weight is like a little bit of insurance,

Cheers Steve

Lehman manual

Kevlar. FYI you'll find a Ford Lehman manual in the Library section of this site.

I use mono grade 30. Not because some guy on TF says so but because my owners manual that was generated w the input of engineers says so. Also I firmly belive there is no need for milti-vis oils. Unless one leaves an engine for years there's plenty of oil film left on engine parts for startups. If it was not so millons of cars would be falling appart. I've read several times that higher viscosity and engine life/wear are directly related. It would seem the highest viscosity oil that can be used w easy startups is the best oil. The very slight increase in friction will cause an quially small increase in fuel consumption. No doubt but I think it's basically fly stuff.

If we needed to start our engines in cold temps or run our engines whereass oil temps get really hot multi-vis oils aren't needed and the extra additives are not helping w lubrication.

I use Chevron Delo 30w.

" It would seem the highest viscosity oil that can be used w easy startups is the best oil."

On the other hand, lower viscosity oils give better fuel economy. My new Toyota uses 0W-20 synthetic oil.

These engines usually run with rather cool oil temp due to the sea water oil cooler. No way would I run SAE 40. 40 won't hurt anything, but unnecessary to be that thick. Run either 30 or 15W40. The reason multigrade was not recommended back when these were built was that multigrade then was not very good. Modern multigrade will be fine in an old ford.

The PO and I have been using 15W-40.

It depends on where you use your boat. What is the coldest engine room temperature that you expect? Cold starts cause a lot of wear. 15W-40 is a good choice.

A couple of additional points re these slippery/oily situations,

1) Lehman manual states 40 mono grade for operating temps above 90 F

2) Example: NC state average temp 60 F (high 70 F) + average engine room temp

3) Now add that average increase of a well ventilated engine room, where as most engine manufacturers recommend max 30 F you are at that magical 90 F easily

4) What we boaties some time forget when we look at an engine manual is that most manuals are not location specific (ie: Truck/Car/Boat etc)

5) Where as the boat installation has probably the most compact under naturally ventilated environment to work in(yes they have an oil cooler) for that very reason, but so do trucks , only difference is it's fresh water cooled and often air cooled

6) There is also a wealth of information available about using multi-grade oils in classic engines that run original type ball bearings.A high percentage of
these individuals who have looked into the subject are very strongly against multi-grade oils for these older engines.They reason that the older ball or roller bearings need a type of oil that does not shear to the same degree as multi-grade oils do at operating temperatures.

7) They go on to say that multi-grade oils when hot, flow far faster and do not give as much protection to the races, as would mono-grade oil.(They call it polymer chain breakdown).

8) So as the oil is being broken down, what first started out as a 20W50, could be as low as a 20W30 after 5000Km.
(Remove or destroy the polymers and you end up with the base oil).

9) Many oil companies tend to agree with this hypothesis, and recommended that oils should be changed more frequently if multi-grade oils are used with older ball or roller bearings.

Just Saying

Cheers Steve

My FL 135's spent their lives up north, Wisconsin, etc. and have had 30W their whole lives according to records. Now the boat is mine in South Florida. With an oil change coming in the not too distant future I have been thinking about this subject. Part of me goes with the traditional "if it's not broke don't fix it" theory, they have made it 4200 hours over 30 years why mess with it? The other part of me thinks that going from Wisconsin to South Florida is a drastic change in operating environment and a step up to 40W might be wise?

firstbase said:

My FL 135's spent their lives up north, Wisconsin, etc. and have had 30W their whole lives according to records. Now the boat is mine in South Florida. With an oil change coming in the not too distant future I have been thinking about this subject. Part of me goes with the traditional "if it's not broke don't fix it" theory, they have made it 4200 hours over 30 years why mess with it? The other part of me thinks that going from Wisconsin to South Florida is a drastic change in operating environment and a step up to 40W might be wise?

Click to expand...

IMHO- This is a classic example of the above temperature variances and why the Lehman manual sets out different oil viscosity for varying temp's,

For me as a an engineer and previous long time Lehman owner it would be a no brainer,

Question: Do you need an Aircon in South Florida?

Cheers Steve

Do I have an aircon in South Florida? Only in everything I own! I even have a small window unit on the dog. Everybody relax, no animal abuse here. He is a very large dog. so I take it my going to 40W would be a good move in your mind? I will say that the manual doesn't mention anything about 30W. For 90+ degrees it says 30W. I guess that is my quandry. Maybe 40W is TOO thick even in these conditions. Unfortunately my dog doesn't use oil or I would try it on him.

Ha Ha! good one! (re the dog)

Yeah some Lehman manuals only show the 30 mono grade but most others including the one down loadable on this forum show 40 mono grade for above 90 F applications(also dont forget the water temp in Sth Florida is way up as well when compared to northern waters so over all your engines are running hotter than way up North)

Its about the thinning of the oil , the hotter it gets the thinner it gets and really between 30 mono and 40 mono there's not a lot of difference(but enough in warmer climates to make a small improvement in the top end operating range,You dont suffer from the possible Northern Cold (very cold) start ups where the thinner 30 MONO may give you an advantage during the first few seconds,

I forgot to mention way back that many think that the W in the oil spec stands for "Weight" where as in reality it stands for WINTER, hence why you dont see the "W" after grade 40 mono,

Finally, Here’s another thought regarding viscosity. It is vitally important to keep internal engine clearances in mind. Looser clearances in the engine and oil pump as they get older/wear require higher viscosity oil to maintain oil pressure.

Quote:Viscosity is the most important property of a lubricant. Understanding viscosity promotes the ability to reduce wear, improve fuel economy and make more horsepower.

Cheers Steve

"On the other hand, lower viscosity oils give better fuel economy. My new Toyota uses 0W-20 synthetic oil."

Vehicle oil is specified to get the best CAFE numbers for a fleet of thousands .

The tiny percentage better fuel economy is important

, but hardly to a boat owner who probably prefers engine longevity..

Somewhere in the Lehman manual temperature and viscosity are noted. Cooler climates you may not want 40, but not sure I would ever go less than 30. If you have an older model, use the same oil in your injector pump.

FF said:

"On the other hand, lower viscosity oils give better fuel economy. My new Toyota uses 0W-20 synthetic oil."

Vehicle oil is specified to get the best CAFE numbers for a fleet of thousands .

The tiny percentage better fuel economy is important

, but hardly to a boat owner who probably prefers engine longevity..

Click to expand...

Let's be clear here. I was not suggesting that anyone use 0W-20 oil in their boat engine unless that's what the manufacturer calls for. I'm sorry if anyone misunderstood my post. The Toyota engine was designed for 0W-20 synthetic oil.

There is a downside to heavy weight oils - It takes longer for the oil to flow on startup and in cold weather. And of course, there's the (minor) cost in fuel economy.

The proper oil to use in your engine is the oil that the engine manufacturer calls for, not something else that some guy on the Internet suggests.

I've been through a few Ford Lehmans, can't remember once seeing ball or roller bearings.

Regarding the 90F ambient temp: It really does not matter. What matters is oil temp. On the Lehman marinization, the oil is cooled with a sea water cooler without any thermostatic control. Oil temp I have measured on FL trawlers is around the 160F range, WAY cooler than a typical diesel. Most diesels use coolant for oil cooling and oil runs around 190-220F. And many of these spec SAE 30.

I suspect the SAE 40/90F ambient spec was imported directly from the Ford literature, where these engines were run in ag equipment and road vehicles where there was no sea water oil cooler. Oil temps then probably a good bit higher than in marine and may be closely related to ambient air temp.

If your oil is running at 160F and your engine is healthy, there is no need to go to SAE 40. SAE 30 is more than adequate. And 15W-40 will not harm a FL.

Any modern oil is WAY better than the stuff they had to work with when the engine was built.

Ski,
Are you saying SAE40 and 30 are not modern?
What is modern oil?
I'd say oil w better and more recently developed additives. Oil is oil.
Synthetic "lube" is modern and better in some ways. I use it in my cars. But I use it for a reason or reasons. NOT JUST BECAUSE IT's MODERN. I assume all or mostly all our boats have heated engine compartments so the lowest temp our boat engines will see is 38 - 40 degrees f. No need for low viscosity at all. And most all trawler engines run rather cool and have fairly light loads. No need for high performance oil. 30W or 40W is 100% satisfactory.

30 and 40W oil today is 100% modern. All the additives are probably the same as multi-vis oils .. just not the extra additives that extend the viscosity range. And those additives are (I think) tiny rubber balls that don't provide lubrication. There's more oil in mono-grade oil and hence better lubrication. So in my opinion mono is better. Only slightly of course but there's no good reason not to use it.

Ski areyou aware of additives in today's oil that multi-vis oils have that mono grades don't? Excluding the viscosity additives.

Another thought is to think about why most oil brands offer mono grades. People are buying them. And hopefully for good reasons. The good reason for us to buy mono is that multi-vis is not needed. However if you have an underpowered trawler (very unusual) and need to run it at high loads and start yourengine in freezing temps and it's powered by a modern engine that is spec'ed for multi-vis then you have need for the MV oil and should use it. My engine is spec'ed for mono and MV oils but the engine is usually found in industrial applications where the engine will need to be started in cold temps. Hence the inclusion of MV.

And MV oil isn't that modern either. 10W30 automotive lube oil was very common in the 60's ... that is 50 years ago.

Willy, I think single grade oils have also benefited from advances in tribology. SAE 30 will do just fine in any of our engines.

One complicating factor is that I think API is no longer testing single grade to the latest standards, so while the oil is still good stuff, it is stuck as being labeled as CF and CF-2 (for two strokes). More improvements have been made to 15W-40 as that is what is mostly used. A bunch of the changes in the specs have been to accommodate emissions changes, and whether those are beneficial to older engines is an open question.

My take is I would have absolutely no problem using SAE 30 or SAE 15W-40 in any four stroke trawler engine. I use 15W-40 in my high output Cummins as that is what they recommend (only 17yrs old!!). But if someone wanted to run 30 in the same thing, that would be fine too. Manual is ok with 30.

Very rare to have engines in our type service have any wear or other failures based on the lube. Super rare. Use the lube you want for whatever reasons, and enjoy.

But I stick with my statement that SAE 40 in a FL 120 is overkill due to the low oil temp.

Thanks Ski,
That about sums it up IMO.

Ski in NC said:

I've been through a few Ford Lehmans, can't remember once seeing ball or roller bearings.

Regarding the 90F ambient temp: It really does not matter. What matters is oil temp. On the Lehman marinization, the oil is cooled with a sea water cooler without any thermostatic control. Oil temp I have measured on FL trawlers is around the 160F range, WAY cooler than a typical diesel. Most diesels use coolant for oil cooling and oil runs around 190-220F. And many of these spec SAE 30.

I suspect the SAE 40/90F ambient spec was imported directly from the Ford literature, where these engines were run in ag equipment and road vehicles where there was no sea water oil cooler. Oil temps then probably a good bit higher than in marine and may be closely related to ambient air temp.

If your oil is running at 160F and your engine is healthy, there is no need to go to SAE 40. SAE 30 is more than adequate. And 15W-40 will not harm a FL.

Any modern oil is WAY better than the stuff they had to work with when the engine was built.

Click to expand...

I believed Ski's info here is right on the money. A significant reason to use a certain viscosity is due to temps at start up to ensure proper flow. The other side is to make sure viscosity is ok when the oil gets really hot but that is not nearly as much of an issue with water cooled oil coolers. I believe that one cannot go wrong either with 30w or 15-40 in a FL. I would be resistant to going to straight 40.

Ken

I don't understand the resistance to mono 40W. As long as one's engine cranks smartly at startup.

As to flow oil is probably close to totally uncompressable so the oil pump revolves so many times X amount of oil advances through the system. If the engine is running oil flow is insured and lower viscosity is not an advantage ... in this regard.

During the summer I often include a quart or two of 40W. Actually I don't think there is much difference in the thickness of 30W and 40W. Not as the numbers lead one to believe. 20W would seem to be twice as viscous (thick) as 40W. I don't think it's even near that. A small difference.

Nomad Willy said:

I don't understand the resistance to mono 40W. As long as one's engine cranks smartly at startup.

Click to expand...

Oil can be very sluggish and thick at startup, and it is imperative that the cylinder walls receive adequate oil to cool them. When oil pours like syrup it can not wash the cylinder walls and remove the combustion heat.

That is why they say wear happens more at startup than at any other time for a motor. Oil starvation. I have seen lots of dirt bikes suffer from the piston seizing up because they never let the oil warm before racing.

.............

That said, I have a good friend thats been grinding cams for better than 40 years and to this day he swears that his empirical evidence shows that a straight weight diesel (rotella) will protect the valve train much better than a multi grade.

.............

I run rotella synthetic in everything I can except the genny. It gets rotella 40w, easily obtained from oriellys. Its so much quieter running with it. To me the quieter running agrees with a straight wt oil being better for valve trains. At least for diesels.

"There is a downside to heavy weight oils - It takes longer for the oil to flow on startup and in cold weather."

I am not so sure of this as oil in most engines is pumped with a geared pump , the days of a finger bolted to the end of a con rod for splash lubrication are gone..

In coaches and large trucks the thin winter oil is used instead of a block heater so the engine can spin rapidly enough for compression temperatures to get high enough to ignite the fuel.

Thin oil is considered safer than using an alternate fuel, Ether, as it is too common for a driver to attempt to start a warm run out of fuel vehicle with the Ether. This can cost the engine.

"Modern " oil usually just means more detergent , as since '96 many engines are fed their exhaust gasses for the air police , which is hard on the engines.

Single weight oil has less modifiers and additives so there is more oil , in the "oil".

Ski's excellent #18 and #20 posts seem on the mark. I might add, use your laser gun to check engine oil operating temperature.