Speaking of Biodiesel - Page 2 - PeachParts Mercedes-Benz Forum

coachgeo · #16 04-27-2003, 11:19 PM

Quote:

Originally posted by LightMan
As for adding straight vegetable oil to your tank for lubricity, I wouldn't recommend it, unless it's heated up before running...snip

In Europe there are lots of one tankers.... as in they dont use diesel at all cept maybe to thin out the WVO when the weather is cold. Some use mineral spirits for the same purpose. With this in mind a pint or even a qt would be so small a % that it would do nothing cept maybe increase your lubricity which is the plan unless of course you live in cold country like Michigan, Minn. Canada, WI etc. and further north .

Quote:

...just add a little biodiesel. Biodiesel is not even close to dumping pure cooking oil in your tank.

I agree with you and think adding biodiesel would probably be better. It would take a little more than food grade cooking oil but thats fine. On the other hand there is far far more places without biodiesel available than there are places with food grade cooking oil available.

The additives you mention if they are not made with biodiesel (some are) then they are petroleum products thus they probably dont reduce emisions cept by improving combustion a litte and they add to the dependency on foriegn oils.. just matters if that is a care at all to u.

Well... guess we have beat this one to death with a stick now

LightMan · #17 04-28-2003, 08:45 AM

Adding a pint of vegetable oil surely won't significantly lower your emissions, may burn funny or coke in your engine, and is a general gamble. Fuel additives, while they may be made with petroleum distillates, are not primarily petroleum. Also, adding 2 ounces of additive is relatively insignificant as far as foreign oil dependence, and you shouldn't be saying anything about that since it sounds like 95% of your (theoretical) tank is dirty petro diesel anyway...

The point is, the addtives definitely work(good ones) to reduce smoke by increasince cetane, adding lubricity, detergency, stability additives, water dispersants etc.. Vegetable oil is designed for cooking, fuel additives are designed for diesel fuel. Use the right tool for the job.

Just recent the ultimate fuel additive(i'd been waiting like 2 yrs) has become available to the retail public. Primrose makes and sells 95% of their product directly for/to the US military. It's used in nearly all their diesel vehicles for years. The proper formula is powermaster 405 unless you live in a winter climate, for which there is another mix with anti-gel added. Second choice would be stanadyne's performance formula, and lastly the cheap but readily available powerservice. Powerservice is 75% diesel fuel though, quite the waste of money/effort. Comparatively, I had to add 10 oz of powerservice to treat my tank, 6-8 oz of stanadyne, and 1.5oz of primrose, the stuff is WAY concentrated. If anyone's interested PM or email me, as far as how to get the primrose, I dont want to post a link here for the forum's sake..

#18 04-28-2003, 11:10 AM

It makes a great deal of difference which model of whose diesel you're fueling. Products of Daimler-Benz from 1985 or earlier will run fine on blends of vegetable oil and diesel, or on 100% preheated vegetable oil, but many newer cars with injection pumps different from the traditional Bosch in-line type and/or with direct injection must, for the most part, be limited to petrodiesel or biodiesel. VW TDI motors seem more tolerant of heated vegoil fueling than most, though. Motors with rotary pumps or common-rail systems are likely to be troubled by the higher viscosity of vegetable oil, and direct injection motors are the ones which exhibit the "coking" problems if run on straight vegetable oil.

On the other hand, my old '85 300TD, with only 318,000 miles on it (turned over another thousand on the way home from church yesterday), has been very happy, for the past year and 13,000 miles, on 40% waste peanut oil (from a popular Williamsburg, VA tourist trap seafood place) and 60% #2 during warm weather, and 20% / 80% when there is a chance that the temperature will drop below freezing.

Many have said on other biodiesel and WVO sites that the reason for the apparent smoother running is not the extra lubricity provided by the veg-based fuels, but rather, that they have a slower burn rate, which would also explain the usual small drop in fuel mileage on either vegi blends or biodiesel; whether this may also increase lubricating oil dilution if an engine is idled or run very slowly for long periods is another issue. Some folks who are into running vegoil have tried advancing the injection just a hair, but that leaves one in fear of burning pistons if you have to fill with a large quantity of #2 while somewhere far from home base.

Meanwhile, I've got to get back to trying to figure out the State of Virginia's 19 page form which has to be submitted monthly to pay the road tax. Main problem is the $2000. bond which has to be posted -- its fees wipe out all the savings for a small user like me.

LightMan · #19 04-28-2003, 01:03 PM

I'm not sure for SVO, but biodiesel actually has a higher burn rate(cetane=measure of combustibility) than #2. The natural characteristics of the vegetable oil it's made from provide the extra lubricity. Not sure where you get your info, but many on the TDICLUB have actually retarded their timing a bit, to compensate for the lower btu's of biodiesel.

What kind of mileage are you getting with your 60/40 petro/peanut wvo mix? Have you looked inside the engine to see that the wvo is burning cleanly?

P.S. you technically don't have to pay road tax on 'fuel additives' or vegetable oil. Vegetable oil isn't tagged as a road fuel, and you(or the original purchaser) paid sales tax on it. Any fuel additive isn't road taxable, so as long as you're not using it as a neat(read=100%) fuel, you don't need to worry about the tax/forms, etc....

#20 04-28-2003, 02:41 PM

My oldest daughter is a senior tax manager for PriceWaterhouse-Coopers and authorities whom I have consulted (who sent me the forms) within the Commonwealth of Virginia Department of Motor Vehicles have agreed with her that the road tax has to be paid on anything used as a substitute fuel under both federal and state rules (some states may have enacted exemptions). #1 Daughter says, though, that ony amount less than $10. does not have to be reported, and since Virginia insists that the reports must be filed monthly and my monthly amounts would be less than $10., I've been hoping to get by on that grounds, although I suspect that somewhere there's some fine print which says $10. per year.

My mileage with the 40% blend has been right about 1 mpg less than with straight #2: 25.5 mpg @ steady speeds in the 70-80 range, but 22 mpg around town.

I did have occasion to examine the tips of three of my glowplugs about 3 months ago and they looked just fine (and attempts to ream the prechambers with the appropriate tool indicated that they were not very carboned-up at all). Besides the TDI club site, I regularly visit the Australian and British dominated site biodiesel.infopop.net -- the Australians have lots of experience with every manner of biofuel.

coachgeo · #21 04-28-2003, 10:45 PM

A pint... even a qt. BLENDED in with your diesel (as in blend it in a bucket with a few gallons before putting it in.... etc.) will not cause any coking. Its to small of an amount. I wont even gel unless ur in cold cold climate. Again its too small of an amount. You wont even need to heat the fuel cause its too small of an amount.

Now yeah.. if you get over say 5% % of vege fuel then sure.... you better make sure your vehicle is one that is known to be Vege friendly. What % is a pint... in a full tank? Assuming 10 gal your talking what 0.25% for a pint and 0.5% for a quart.

Even Direct injects will be ok with that, but they dont need the added lubricity cause they are designed to run with the newer diesel fuels anyway.

By the way, Most all (Actuall I bet ALL) of the Direct injection motors still use a chamber to aid in automizing of the fuel. Some refer to the old prechamber in IDI engines as "swirl chambers" and this in reality is all they are. In DI engines all they did was move the swirl chamber to a new location and then inject directly into this area. Hince one reason for the name "Direct injection". This is straight from Elsbett "Multi fuel" technology. The new chamber is TADAAAA..... the top of the piston!

The theory is that the VW is most tollerant to alternative fuels cause their pistons have the deepest and most efficent chamber on the top of their pistons out of all Direct inject engines and their spray patterns of their injectors utilizes this best by spraying a more centralized stream of fuel into the pistons chamber. This means no unautomized (probably none anyway) vege fuel is hitting cylinder walls.. or edges of piston where it can get to the rings. Course good automization also means it gets burned better thus again it still never hits the cylinder walls or gets to the rings etc. The vege fuel that hits these areas is what causes coking. Injector tips not allowing the Vege to form a drop or a film on its head is a big factor too. This drop/film will coke as well.

All this is off the top of my head from lots of reading so feel free to pipe in and correct any wrong assumptions I've made or bad choice of wording in my descriptions of the technicals.

Time to Veg.