Talk Morgan Forums Community Vehicle Talk (non-Morgan) Fuel for thought

Ethanol
Q: Forecourts are moving from E5 specification 95 octane petrol with up to 5% ethanol to E10, that contains up to 10%. Should classic car owners be concerned about this?
A: No. The percentage of ethanol does not have to be displayed if it's no greater than 5%, so many people have been using E5 without realising it. If that has not created a problem with their fuel pipes and seals then neither should E10, as the switch from 0% ethanol to 5% is a far bigger test for their components.
Q: Is ethanol likely to cause corrosion in older fuel systems?
A: Contrary to what is often quoted, the ethanol used in petrol is not hygroscopic. It is miscible with water though, more of which can in fact be harmlessly dissolved by E10 fuel than E5 - in this state there is no risk of corrosion. However, in such extreme circumstances as an excess of water content, falling temperatures and low fuel level, the water can separate from the fuel - in which case steel and even plastic or coated tanks are vulnerable to corrosion.
Petrol, with or without ethanol, can effect the brass and copper components used in some older fuel systems. This can accelerate the degradation of the fuel, especially in rising temperatures.
Q: How can owners avoid such problems?
A: Use only quality fuels. These contain high grade performance additives including corrosion inhibitors - this alone should prevent such issues. If it does not, then the careful of a recognised aftermarket inhibitor may help. Also, try and maintain a regular throughput of fuel and avoid leaving tanks low on petrol for extended periods. Using E10 petrol rather than E5 will also reduce rather than increase the risk of corrosion. Premium fuels (i.e. 97-99 octane) do not contain ethanol.
Q: Some believe ethanol can also cause: vapour lock, hot start problems, sticky deposits from dissolved sealants, and even the destruction of some types of fibreglass motorcycle fuel tanks.
What are your views on these observations?
A: We have no personal knowledge of the motorcycle problem. If the others have not been experienced when using E5 petrol, then there should be no issue with E10.
Winter Lay-ups
Q: When preparing cars for short-term storage, what should one do with the fuel system?
A: The tank should be brimmed with quality fuel. This minimises evaporation and the ingress of water, and therefore corrosion. It also prevents seals and gaskets from drying out.
Unleaded fuel
Q: Some classic car owners converted their engines for use with unleaded fuel through fear of valve seat recession. Was this necessary?
A: In most cases, not really. We did a lot of tests prior to the withdrawal of leaded fuel and only encountered problems when engines were subjected to sustained high revs - a situation generally limited to classics involved in motorsport.
Hardened exhaust valves do, however, make sense for anybody wishing to completely rule out such a problem. The use of a suitable lead replacement additive is another option. The potassium or sodium-based ones are the only effective types.
Fuel quality
Q: One would expect BP to champion the use of quality fuels, but why should classic car owners stick to the major brands and what are the pitfalls of not doing so?
A: Quality brands benefit from:
- A good base fuel
- The most effective choice and dosage of additives
- The optimum path from the refinery to the forecourt
The same cannot be guaranteed with lesser brands, and the delivery cycle in particular is sometimes compromised allowing for example:
- Petrol to be contaminated with diesel fuel
- A mix of octane ratings
- Contamination by blended solvents
Such outocmes will inevitably affect engine performance and can promote such longer term problems as component corrosion, contamination of fuel injection systems, etc.
Safety Considerations
Q: Years ago, motorists sometimes moved fuel from car to can by syphoning - a process initiated by sucking the fuel into a plastic pipe. Is it sensible to do this?
A: No!:
- Petrol should never be allowed to enter the human mouth, let alone the lungs, which could ultimately prove fatal
- Petrol is a hazardous substance and ideally belongs nowhere else other than garage or car tanks, or purpose designed cans, for which there are strict laws governing usage and storage.