First of all, let’s be clear; a TDI is not as forgiving on waste vegetable oil as other engines. It’s a direct injection engine, and like all direct injection engines, it’s just not as capable of the sort of “complete” combustion of vegoil as an indirect injection engine, or a swirl-chamber engine.

If you’re thinking of converting a TDI, the first thing you need to read is the following, which is a list I put together for one of the forum discussions on this topic a while ago, and which has since been edited by myself and by my associate, Craig Reece, over at PlantDrive.com, the web site that serves the USA market. (No, Joe did not do many of these things, he went more with the usual advice of settling the oil a few weeks, he used a single 6-port valve, etc. A very basic technique and setup.  BUT,  he does do a LOT of highway driving, and he uses the original-spec European synthetic oil,  and these factors have likely been key to the longevity of this particular engine).

So, here are the “best practice” recommendations:

How to Avoid Problems with a VW Tdi or Tdi/PD Converted To SVO

1. Change lube oil more often, at least 2/3rds as often as usual, for a 2-Tank setup (which is all we do for these engines), and twice as often if you are attempting any sort of single-tank setup (which we don’t sell, but “twice as often” is the standard practice in those cases, according to most of the reputable research). By the way, this is valid for ALL direct injection engines.

2. Get lube oil tested on a regular basis and use a true, full-synthetic  motor oil. (Fluidlife.com in Edmonton is a good lab, and can provide the inexpensive “oil thief”  suction device and sample bottles needed to draw samples out the dipstick hole. Then you just mail them in, and they send you a report.)

Very good is Mobil’s Delvac 1 or

 Mobil 1 “TurboDiesel Truck Oil” which is the same product. Please note that no other Mobil 1 oil is a diesel-specific oil.

Amsoil also offers a very good diesel-specific synthetic motor oil. Google around, you’ll find it.

Petro-Canada and others also make a good, true, full-synthetic.

3. Use two, and preferably 3 (for faster purge times), 3 port valves and a controller of some sort. We sell the VOController, which is the most feature-rich controller on the market.

Two 3-port valves, if sequentially switched during the “purge” cycle,  will prevent cross-contamination of the diesel tank with SVO. See: http://www.plantdrive.com/html/faq.html#30, “Cross-contamination with a 6-port valve, a problem or not?”

5. 5.Use the best vegoil and best prefiltering techniques you can. You want the fuel oil to be especially clean, water-free and as close to pH-neutral as possible. Don’t run junk. Look for good Canola WVO, as close to new as possible.
   

You can buy a water-testing kit from Utah Biodiesel Supply: http://www.utahbiodieselsupply.com/biodieselwatertestkit.php

and you can use it to test your SVO for water.

See also: http://www.plantdrive.com/Used_Cooking_Oil_Fuel_4_18_07.pdf

6. Get the injectors rebuilt or exchanged at time of conversion if the engine has over 100,000 km on it. 

7. Do not add performance modifications such as power chips or modified injectors.

8. Do not even think of single tank on these unless it is a well proven conversion to fully optimize the engine for vegetable oil of the type you intend to use, and has been designed for your climate, and you are willing to follow all the recommendations of the supplier.

9. 9.At the first sign of rough running, poor starting, reduced fuel economy, unusual increase in lubricating oil consumption, increase in lubricating oil level on the dipstick,  reduced power or unusual increase in black smoke, or any smoke, start investigation of possible causes
   

10. 10.Make sure you get that engine out on the highway, and give it a long hot run often, and do an "Italian tuneup" (full throttle run through the gears) once a week.
    

11. 11. Avoid idling and low engine loads on SVO. If you are stuck in traffic or doing an lot of stop-and-go city driving, get a Hybrid. That’s where they shine (and conversely, where they do NOT do well, is on the highway...a TDI will give you better fuel economy, typically).  A TDI is for the highway, and regular trips of at least 15 minutes at a time should be the norm.
    

12. 12. Ensure your SVO is hot enough, consistently, under all operating conditions, as much of the time as possible. 158F/70C target temp, preferably hotter, in the 80-90C area.
    

13. 13. Make sure the SVO is not *too* hot (limit to 212F/100C.) Our Vegsensor will limit our Vegtherm Standard to about 95C.
    

14. 14.Install an Amsoil bypass oil filter kit, available from Diesel Geek: http://www.dieselgeek.com/servlet/Categories?category=TDI+Bypass+Filter+Kits
    

15. 15.In cold climates, install a good engine heater, such as the TDIHeater from FrostHeater.com. This will speed warmup time, and allow you or your controller or SVSW50C Early Switchover Preventer to switch to vegoil sooner, by preheating the engine prior to startup.