Talk Quesada forum

My mechanic back home told me that when you have a service the car is tuned to the fuel you have in it at the time so changing it isn't the best thing to do . . Going back a few years the advice was to keep to the same brand of petrol as say, BP was different slightly to Esso etc. But these days most stations, even the likes of BP etc. Get their supply from the cheapest option at the time so you can't tell . . If your car runs a bit lumpy change the place you get it from rather than the octane . .

Ok some good answers, but not precise.

Octane rating is a measure of a fuel's ability to resist ‘knock’. The octane requirement of an engine varies with compression ratio, geometrical and mechanical considerations and operating conditions. The higher the octane number the greater the fuel’s resistance to knocking (pinking, or pre-igintion). As the mixture compresses, it may detonate prematurely, rather than ignite and burn, ie before the optimum compression has been reached. This creates a shock wave in the cylinder, and this shock wave can, over thousands of miles, damage the valve seats, because it causes excessive heating of the cylinder.

Your engine is set up to use a specific octane, you should check what it is in the user manual. Putting 95 octane in an engine set up for 98 will provide reduced power, whilst putting 98 in a 95 may cause pinking. either way the engine setup may need adjusting to prevent pinking.

The old Sierra 2.0L with the Pinto petrol engine were staggeringly adaptable. Several time when there were petrol shortages in Uk, i ran it on a mix of half 98 octane and half diesel. It pretty much worked, just wasnt as nippy....

On the other hand, my father was an engineer, he used to design prototype oil and diesel engines, and gas turbines. He designed a crude oil engine for the middle east that would run on anything from Crude oil straight out the ground to neat vodka, with some adjustments.

98 Ron is for performance engines, if you are running a Ferrari, Porsche or similar then it is better. Newer (every day) vehicles are designed to run on much lower Ron numbers,we was in the USA this year and they have introduced fuel that has a high percentage of ethanol, burns more lean, lower emissions and costs much less not long before its rolled out in Europe hopefully.

richardlionheart wrote:Ok some good answers, but not precise.

Octane rating is a measure of a fuel's ability to resist ‘knock’. The octane requirement of an engine varies with compression ratio, geometrical and mechanical considerations and operating conditions. The higher the octane number the greater the fuel’s resistance to knocking (pinking, or pre-igintion). As the mixture compresses, it may detonate prematurely, rather than ignite and burn, ie before the optimum compression has been reached. This creates a shock wave in the cylinder, and this shock wave can, over thousands of miles, damage the valve seats, because it causes excessive heating of the cylinder.

Your engine is set up to use a specific octane, you should check what it is in the user manual. Putting 95 octane in an engine set up for 98 will provide reduced power, whilst putting 98 in a 95 may cause pinking. either way the engine setup may need adjusting to prevent pinking.

The old Sierra 2.0L with the Pinto petrol engine were staggeringly adaptable. Several time when there were petrol shortages in Uk, i ran it on a mix of half 98 octane and half diesel. It pretty much worked, just wasnt as nippy....

On the other hand, my father was an engineer, he used to design prototype oil and diesel engines, and gas turbines. He designed a crude oil engine for the middle east that would run on anything from Crude oil straight out the ground to neat vodka, with some adjustments.

My manual just says use at least a 95 octane or higher. I suppose next time i'll fill up with 98 and see what benefits (if any) i get.

I remember using 2 star leaded petrol (very cheap) many , many years ago !