Better mileage, smoother running engine?

[Grizz]

Another story for ya'! (Obviously, I don't have much to do on a rainy day.) :)

Back about a year ago when Excalibur Coach in Sanford was doing the fuel tank and system cleaning on my Country Coach (glass coach), Doug Stolfo the owner recommended a fuel additive product.

Having been a new car dealership Service Director for half my career life, I never believe in “Mechanic in a Can” products like oil and fuel additives.

Anyway, Doug told me about Lucas fuel additive and how if corrected a rough running DD series 60 he had that idled rough and didn’t have a lot of power. He tried the Lucas fuel additive (doubled up on the recommended amount) and by the time he had driven 1200 miles, he was astounded at the difference in performance and the engine idled much smoother. He recommended I try it in the CC. I did!

‘USUALLY’ rough idle, poor performance and low fuel mileage in diesel engines are caused by dirty or worn out injectors. Dirty injectors are USUALLY the result of excessive slow idle, low speed stop and go driving, lack of use. etc.

Before using the additive I was getting just over 8 mpg on average. I ran two tanks of fuel through the engine with double the recommended amount of Lucas. On the 2nd tank of fuel the mileage was better. By the 3rd tank and thereafter the mileage was almost 9 mpg and the engine idled better. (Cummins 350 in a rather light coach.) Okay, maybe this newer additive stuff is better than what they were selling 30 years ago.

When I bought the current Marathon, it idled rough and the mileage was just over 6 mpg. (6.2 on the computer) After a couple of tanks of fuel with the Lucas additive, the engine idles smooth, acceleration from a stop is better and after a 2000 mile trip the average mpg is 7.15. I doubled up on the amount of Lucas additive for two tanks of fuel.

I now add the recommended amount of Lucas to every tank of fuel. Lucas claims it will pay for itself in added mileage and I agree to that and more. The coach runs great, it idles smoothly and I’m happy with the mileage.

[Gil_J]

Grizz,

Your results are inline with what many boaters have told me in the past.

I wonder how these additives perform and their effect on 2007+ EPA engines and DPF.

[Grizz]

Did you mean DEF - diesel exhaust fluid? According to the research (I did) the Lucas fuel additive is compatable it the newer diesel engines and with the use of engines that require DEF.

I don't know! At my age to come to grips with a 'Mechanic in a Can' concept is rather strange, but darn - it did the job!

Watch for my next report on Lucas ENGINE OIL additive. When I was over at Florida Detroit Diesel in Orlando (to reset the Jake/Downshift action), I noticed Lucas ‘engine oil’ additive on the parts counter. They recommend adding it when changing the oil. I will do that next oil change and report the results on this forum.

For some time Lucas additives have been known in the automotive industry as a brand that actually works as claimed. So far, I'm a believer!

[Gil_J]

Diesel Particulate Filter is what I meant. These exhaust after treatment systems contain their own fuel injector for super heating of particulate matter that has accumulated in the DPF. I am not concerned with the DPF injection system but rather any affect on the particulates that are produced through the normal combustion process in the engine and then sent to the DPF.

Generally, engine manufactures don't recommend additives. This could be because they are bad, there are too many formulas to give blanket approval or they just don't want to accept any liability.

Keep us posted on your findings.

[travelite]

Thanks Grizz,

I'll reach for some Lucas Fuel Additive at my next fuel stop. For a bit of additional fuel lubricant I've been using FPPF's Fuel Power. After 5500 miles I do achieve 7+ mpg, but the S60 does idle roughly. At 73K miles I'm probably about ready for a tune-up. In the meantime I'll give Lucas a try. Thanks! :)

[dale farley]

Grizz,

Is this the additive you are referring to? As Gil mentioned, others (including DD) have said we should avoid any additives, but your results surely make it sound very interesting.

[Gil_J]

Tune-up...really? Besides a valve adjustment at 100K or so, I'm not aware of what they would even adjust. BTW, at the valve adjustment I also understand they check/adjust the Jake valves. FWIW and maybe we should take a poll, I understand few actually have the valve adjustment done. Some don't because with some conversions there is a lot of dismantling in the bedroom to access the valve cover. With other conversions the valve cover can be removed from the engine bay.

After a 14K mile trip from FL to AK my average fuel mileage was just over 7 mpg. I'm happy with that and even happier on the east coat where my mileage is typically better than 7.5 mpg. Coming from the boating world where they measure fuel consumption in gallons per hour, I'm a happy camper. When gallons per hour are translated to miles per gallon it's scary. I almost always had trawlers where I would get an amazing 3 mpg in a 50-footer. A client had a 78-foot traditional yacht with two 1300 HP CATs. On his deliver cruise, that I crewed on, he was using over 100 gallons per hour at speed. That was nearly 5 gallons per mile!

[travelite]

Hi Gil,

Yes, adjusting the valves is very important especially for the EGR engines. The tuneup procedure also involves setting the injector height which effects the metering of fuel into the cylinders. It's no surprise that one of the tip-offs that a tuneup is required is a marked reduction in fuel mileage. Typically owners let the fuel mileage dictate their tuneup needs. A loss of 0.5 mpg can be restored by a good tuneup. Detroit Diesel Guru, Gonefishen, over on dieselenginetrader.com outlines strict valve setting requirements on the EGR equipped S60's noting that popping and engine backfiring at lower rpm's is often associated with tight valves on the EGR engines. The non-EGR S60's require periodic tuneups to restore fuel mileage.

[dale farley]

I wonder if there is any way we can tell if the valves on our particular conversion can be accessed without tearing into the bedroom? Has anyone had it done solely via the engine compartment, and if so, what is the clearance over the valve cover?

[Gil_J]

David,

I agree that valve adjustment is important. The million dollar question is how far out of tolerance are valve settings at that first scheduled adjustment? Is it a feel-good maintenance procedure or really needed? As for injectors, what would affect the injector height over time?

Dale,

As I've been told, if the Prevost engine box hasn't been altered, there's room to remove the valve cover. Even when it can be done from the engine bay it must be a PITA to get your eyes on the adjusters, especially the ones furthest forward. Your coach is one that would be a PITA along with other conversions were the passenger side access is nonexistent. I'm guessing that on yours you would have to remove the house batteries and tray structure. Don't ask for help...

[dale farley]

Gil,

Preparing mine for service would give you some valuable experience!

[Grizz]

When the injectors are dirty, the engine produces more than normal amounts of soot, which shorten the life of the DPF. Dirty injectors don’t spray the fuel properly causing incomplete combustion. Usually the first signs of dirty injectors are: rough idle, poor acceleration (from a stop) and lost fuel mileage.

I agree! Engine manufacturers generally don’t recommend fuel or oil additives for the reasons Gil mentioned. However, anything that makes the engine run better has the potential to reduce particulate while improving performance and MPG. In the cases I described the Lucas fuel additive corrected rough idle, acceleration and increased MPG.

Using an additive like Lucas does not negatively affect the DPF, but to the contrary would extend the life and performance of it.

Much of the lubricant has been removed from diesel fuel in the ultra low sulfur process. Lucas fuel additive puts it back in through a process that is way beyond my knowledge. http://www.lucasoil,com for further facts!

The photo that Dale posted is indeed the additive I am using.

I don’t think Florida Detroit Diesel would be recommending Lucas if weren’t safe to use and have had good results with it.

[travelite]

David,

I agree that valve adjustment is important. The million dollar question is how far out of tolerance are valve settings at that first scheduled adjustment? Is it a feel-good maintenance procedure or really needed? As for injectors, what would affect the injector height over time?


Hi Gil,

Just the normal stuff: wear on the silicon nitride cam follower rollers, wear on the injector shaft, thermal cycling of the engine. Here's some info from the experts over on www.dieselenginetrader.com (http://www.dieselenginetrader.com/diesel_talk/messageview.cfm?catid=9&threadid=3109). A full tune-up includes setting the valves, jake brakes, and injector heights.

[Mikee]

The H3s do not have bedroom engine covers, they are accessed from the engine compartment. The XLIIs have the engine hatch set up.

Mikee