Depends on the engine, and whether or not it's been converted to run on unleaded fuel (ie hardened valve seats fitted). General rule of thumb is the older the engine and the lower the compression ratio the lower grade octane you need, and if you're using unleaded fuel then it's good practice to dose the fuel with an additive at every re-fuelling. Views differ on whether or not this is necessary, but it doesn't adversely affect the engine if it's really not needed. However, if it IS needed and you don't use it, you won't find out until the damage is done and you then need fairly pricey repair work on the cylinder head. For the low costs and mileages involved for a Bug it's best to play safe imho.
So ordinary unleaded (95 octane/RON) should be fine, but I would advise you add an additive for unleaded fuel. There are several on the market, a few coins from Halfords. The one I use is Redex Lead Replacement Fuel Additive, 250ml bottle. I carry a 10ml syringe with it, obtainable from eBay (I got mine from a printer ink refill kit, also from ebay) and I use 6.25ml per 5 litres of fuel. So, I know roughly how much fuel I am going to put in - say 15 or 20 litres. I open the filler cap, squirt in the appropriate volume of additive, then fill up from the pump and the fuel washes the additive down and mixes it up. Seemples. You might want a small towel too for any drips.
Remember to read the instructions - different additives will probably use different dosing amounts.
Whether one uses an additive or not is up to them, but there *are* technical risks running an engine designed for leaded fuel on any unleaded fuel, and for the costs of an additive to address these issues, one may consider the money spent versus the costs of repairing engine damage is a sensible investment.
Whilst it does seem true that alloy Reliant engines had hardened seats (http://www.world-of-reliant.org.uk/phpBB3/viewtopic.php?t=1307&sid=1f8942848088bddafcaf597459568be8) it is NOT the case that just the valve seat is at risk. The valves also can suffer damage, and as well as preventing pinking, the lead content in the fuel also provides lubrication to the valves.
A bottle of Redex costs £5.69 for 250ml at Euro Car Parts today. I use 6.25ml for 5 litres of fuel, so my 250ml at £5.69 will do for 200 litres of petrol. At £1.30, say, for a litre of petrol, 200 litres costs £260.
So I am adding £5.69 to a fuel spend of £260. That's raising my fuel cost by just over 2%.
Suppose I buy petrol at £1.32/litre. Then next week I buy it at £1.28/litre. That 4p/litre difference is actually a 3% variation in price. So the money I am 'burning' by using the additive is actually less than what you see as a daily variation in fuel prices anyway, and probably don't give a second thought to.
What I advised "imho" is that you have nothing much to lose by using the additive, and possibly a substantial expenditure to avoid if things go wrong - but that *is* just my opinion. I also wrote "Views differ on whether or not this is necessary" as this thread demonstrates
redex is not a lead replacement additive, a proper lead replacement additive from millers oils is about £25 for 250ml and only treats 55ls of fuel
This is from the Redex/Holt International UK web site:
"If your car is designed to use leaded petrol, using unleaded can seriously damage the engine and reduce power. This is particularly a problem for older classic and vintage cars.
Redex is dedicated to keeping cars driving, even those not designed to use today’s modern fuels. Redex Lead Replacement can be added to your engine with unleaded petrol to provide your car with the additives it needs. It lubricates soft valve seats and protects them against damage. Use regularly in any car designed to run on leaded petrol to maintain performance."
Miller's is of course a well-recognised and reputable brand of lubricants, but at the price you quote I think I'd want it to check my tyre pressures and wash the windscreen as well !
As for "Redex Lead Replacement [can be added to your engine]" being "not a lead replacement additive", I'm at a loss to think how else it might be described...?
I must saythat your knowledge of everything technical is amazing.however the redex additive doesn't raise the octane level doesn't protect against e10 fuel doesn't protect against stale fuel.i have checked out the price of millers the cheapest is about £18 but it only treats 50litres ,valvemaster is similar.what I cant understand is how redex can have the same properties for a quarter of the price and treat four times the amount of fuel as its competitors
I think it might help here to step back and look at exactly what we're talking about. The OP asked "what petrol should I use?". I suggested (and it *is* only a suggestion) ordinary unleaded, with a lead replacement additive.
The Millers product you are talking about is more of a 'whole car' treatment, and yes it claims to do lots of things, and is priced accordingly. But that rather misses the point. The point at issue is what damage could be done to the engine by using unleaded fuel, and the primary answer is damage to the valves and seats area. Why does this matter? Because repairs are expensive and involve a lot of engine strip down. Ergo it makes a lot of sense to pay a modest amount of money to avoid such an issue and Redex LR addresses this - but only this.
The Miller product does this too of course, but it also addresses other issues such as E10 and octane rating. However, these are not issues relevant to the OP's question. E10 may well do all the nasty things claimed of it, but the cost of replacing the damaged parts - seals, tubing etc - is not high, and the work involved is neither major nor technically demanding. Replacing fuel lines is not in any way comparable to stripping a head, cutting new seats, fitting inserts, replacing valves and springs, new gaskets and so on.
Similarly raising the octane rating is not an issue which may cause engine damage other than by pinking, and the Redex LR product addresses this (as it's pinking that causes the valve area damage). If you want to run a higher octane fuel that's fine, but you don't risk engine damage and strip down if you stick with ordinary 95 unleaded.
There are lots of additives you can add to fuel, to get cleaner burning, or reduce sludge, or clean the injectors and so on and so on, but you don't risk serious and costly engine damage if you don't use them. Not using a lead replacement additive *does* risk that damage.
If you want to spend even more money for other functions as well, that's fine. I'm sure owners of high value classics like Rollers and Ferraris would think it money well spent to use the Millers product. Whether it's economically sensible on a Bug is more questionable, in my view. But that *is* only *my* view
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vannin: hi Steve, is this for you and if so how tall are you ? more interest and responses if you use the main forum !
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allan: Does anyone know what thread and diameter of the water temp &oil pressure senders on my 700e ,bug no 50
Jul 5, 2021 21:20:32 GMT
Stiffy: Allan just seen your question. Your better of asking a question on the main site as no one seems to respond to the shout box. cheers stiffy.
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