Petrol:

Unleaded petrol has been the primary fuel on sale now for the past 20 years.
For a while LRP – lead replacement fuel was on sale, but has now all but vanished from garage forecourts. There are still a few specialist garages selling old fashioned leaded petrol. These outlets are few and far between, fine if you live close but not so handy if you are travelling around the country.
The practical solution is to use one of many additives as recommended by the FBHVC. The important thing to remember with these is not to mix the different types. There are several different “chemistries” involved and they are not compatible. Best to stick with one brand.

But does your Land Rover engine need leaded petrol or additives to run without destroying the engine? This is a mute point. Leaded petrol deposited a film on the edge of the exhaust valve and seat which protects the metal from the high temperatures produced by combustion. It’s the exhaust valves that suffer. It is said that “lead memory” can persist for many thousands of miles. Most Land Rover engines are not run on the limit and there appears to be some basis to this.
If the valves/seats were suffering you would notice a phenomenon called “valve seat recession”. What this means is that the valve clearances will close up over a period of time. If you are having to continually open up the gaps on your exhaust valves your engine is not protected and you need to take some remedial action.

Convert to run on unleaded petrol: Many owners have already had the valves and seats replaced in their cylinder heads. This need not be such an expensive process. Most engine re-conditioners can replace the exhaust vales/seats for around £100. Some owners opt for a fully re-conditioned head and possibly some gas-flow work, often known as a “stage-1” tuned head. These are done on a head exchange basis and the cost start from around £250 depending on the work involved and the state of your old head. An unleaded head conversion is a must if you are contemplating running on/converting to LPG (autogas).

So the bottom line is: you can run your Land Rover on unleaded petrol. The engine won’t die instantly. You may never experience valve seat recession. There is no easy way to test if the valve seats have been replaced. You should note that the modern RON fuel specification is not the same as the old octane rating. Modern petrol has nowhere near the octane rating of leaded petrol as sold in the 60’s and 70’s when the Series 2s were new. Adjust your static timing accordingly. (details in the Ignition section)
The other thing to note is that by law petrol now contains 5% of ethanol as a bio-renewable component. Land Rover engines seem to cope with this, but there are (or were) plans to steadily increase this “bio” component and it is not known what the long lasting effects of this will be on older engines.

Diesel:

Over the years the quality and specification of diesel fuels has changed. Today virtually all diesel sold at the pumps is “Low Sulphur” an attempt to reduce pollution and emissions.
Unfortunately the sulphur content (found naturally in crude oil) also helped to lubricate the CAV injection pumps. Modern diesel is a little less viscous as well. Whilst modern diesel engines are designed to cope the older Land Rover diesels can struggle. For this reason it is not a bad idea to run with one of the many diesel fuel additives. Millers Diesel Sport Plus is a good choice. These additives also help keep the injector nozzles clean and they increase the cetane value of the fuel (just as higher octane values increase the power from petrol). Most of the branded diesel garages also sell a higher value diesel, e.g. Shell’s Diesel V-Power or BP’s Diesel Ultimate. These fuels cost a few pence per litre more, but you will notice the extra power and performance. You could try every 3 or 4th tank full with these to see if you benefit. The extra cost may negate any benefit you feel you get.

Recently there has been a lot of interest in biodiesel. This is fuel derived from oil seed crops. This fuel has been processed and is to the same specification as pump diesel (low sulphur) and should be fine for Land Rover diesel engines. In fact the lubricity of the fuel is good and it is blended with low sulphur diesel as and improver at around 5%. In fact most diesel contains a bio-element, it’s just never reported on the pumps.
The problems come when you try to run your engine on straight vegetable oil. Many modern diesels are able to run so. Unfortunately for the older Land Rover engine with CAV injector pumps you will quickly destroy the pump. Vegetable oil is too viscous (particularly at low temperatures) and again there is no lubrication for the pump and the oil attacks rubber pipes and seals. Even running with say 10% oil mixed with pump diesel could be putting the pump at risk. In any event at the moment vegetable oil prices are higher than pump diesel. A popular alternative is the processing of waste vegetable oil into diesel. You can even buy home kits to process your own oil. In theory such fuel is OK to use, but as a precaution use a fuel additive so you know the pump is being looked after. The problem with DIY fuel production is consistency between batches. Strong acids or bases are required in the processing and get the quantities wrong you could end up dissolving the metal in the cylinder head (especially if you have an alloy head). So follow the instruction to the letter. There are likely to be more commercial outlets for processed waste oil and this fuel should be processed to a reproducible standard.

So whilst there are “alternative” sources of diesel fuel, for the Land Rover engine it is best to stick with the major pump brands or supermarket fuels. Use an additive or the occasional tank of high performance diesel to help keep the fuel system clean and the pump happy.

Click here for information on LPG Conversion

 

24th June 2009