Engine Oil and Veg Oil Motoring
The Importance Of Regular Engine Oil Change - Especially When Driving On Vegetable Oil
ALL diesel engines have a certain amount of fuel to engine oil contamination to a greater or lesser extent dependant upon many things. Pre-combustion chambered engines tend to suffer less than direct injection engines. This is why, on any diesel, when engine oil is changed it immediately appears black again - this is soot / carbon deposits amongst other contaminates.
When diesel contaminates the engine oil it thins it out but then most evaporates. When veg oil contaminates it thickens the engine oil due to polymerisation and there is no evaporation.
When engines are started from cold on SVO (Straight Vegetable Oil) or a mix (a blend of veg oil and diesel), this ingress can be greatly accelerated. If you find that the dipstick level is rising and the sump is filling up, it is a sure sign that your engine oil is being contaminated with veg oil. If left unchecked an overfull sump can cause damage.
A simple test for polymerisation is to dip the dipstick then get sample oil between thumb and forefinger. If this is sticky, change the engine oil.
In extreme cases where the engine has gone way over its service interval and/or engine is not in good repair the engine oil can turn to sludge.
With converted engines in good condition this does not usually happen until normal service mileage is due, if at all. However as a precaution we recommend and engine oil change every 5000 to 6000 miles. A good mineral based oil or semi synthetic oil is ok for some engines, but a high spec plant based engine oil such as Plantomot 5w40 is even better as these oils resist polymerization well, conserve energy and are biodegradable.
For peace of mind, keep an eye on your engine oil levels and always change regularly.