I have an old petrol lawn mower that I have always used leaded petrol in it. With the disappearance of LRP I need to know if I can use unleaded in this engine. Do I need an additive of some sort?
Thanks,
Phil
It will probably not run well and you may burn the valves.
Go to a decent car accessory shop and look for additive for the petrol, to make it suitable. A bottle of that will last you ages in a mower.
I doubt it very much, the 'mileage' that lawnmowers do is such that the valve erosion/wear that results from using unleaded petrol will be unlikely to occur until well after the mower has fallen apart for other reasons.
I assume that it runs/ran on 'two star' leaded petrol and thus doesn't need the octane rating of 'four star'. Most mower engines that I've come across would probably run on 'no star' petrol, they're neither high compression nor highly tuned in other ways, no need.
why not just buy the odd gallon of four star leaded. it is still available country wide.
mrcheerful
Not that I have seen,. Just LRP, which sadly is NOT the same.
Dnager is valve burning...higher combustion temps. But probably not worth worrying about.
It ran... until it ran out yesterday, on 4-star petrol, but I cant find a garage locally that stocks eiher 4-star or its replacement.
A variety of answers here... its an old mower but its a trooper so I dont want to speed along its demise
Hmm... still not sure what to do
Isn't it still available in small quantities for vintage car enthusiasts? Don't know how you get your hands on any, though.
Do you know how old the mower is, and who made the engine? If the manufacturers are still around, they may be able to advise you whether leaded fuel is really necessary.
I've just looked at the destructions for the Briggs & Stratton engine on my nearly 20-year-old mower - and that recommends lead-free fuel of at least 77 octane (paraffin?) but says that leaded may be used, but will result in more combustion deposits.
enthusiasts?
You probably look at this site -
Should have done this to start with (newbie error). Went on the Briggs and Stratton engine website which says it recommends unleaded for all of its engines, old and new...problem solved
Thanks for the fast and courteous replies :)
Phil
LRP should be OK.
Failing that, places like Halfords do fuel additive especially for using unleaded petrol in 'leaded' engines.
sPoNiX
You can still get leaded. There is a garrage just off the A55 neer Chester that does it.
Rick
Could be a long way to go on a lawnmower Rick ;-)
All the best ..
T i m
Doesn't surprise me. Back in the beginning cars used to run on unleaded, before softer valve seatings were used and a need for lead to be added arose. Leaded petrol is almost a new thing!
I would imagine that the Briggs' motor you have is built to such loose tollerance that it would be happy on pretty much anything.
The octane value of 4 star versus "no" star is not the issue here the problem is that all of these older engines need lead in the fuel to run without burning out the valve seats
Exactly my thoughts.
"I'm just popping out to get some petrol for the lawnmower dear. I'll be back in 3 days.....".
PoP
I know that, hence my first paragraph.
However the octane rating is also relevant, if the engine requires '4 star' (i.e. about 98 octane) it will pink/knock on ordinary unleaded. That too will eventually damage it. However, as I said, it's very unlikely that a mower engine will need the octane rating of 4 star (hence my second paragraph).
As the OP has discovered anyway, many 'non car' engines like his Briggs and Stratton were designed to run on unleaded petrol years before cars got around to it.
Aren't Briggs and Stratton American anyway? They have been unleaded for some time...
Colin
I think its mnore a point that they were barely designed at all. I mean I was astonished to see, on inspecting a potential new lawnmower, that the B&S (aptyly named) 'engine' now sported what the salesman called 'overhead cam sir' ..subesquently identified as merely overhead valves. Car engines dropped side valves in about 1960 from memory. Briggs and Stratton have continued to use them to this day. Brigs and strattons are big chunky long stroke chuggers, well suited to running off anything from pink gin to fermented cat droppings. 80 octane is probably enough to run them, but starting might be hard...nevertheless a little lead probably improves valve life. However my last B&S got nicked after 9 years and as still in perfect working order having run unleaded all is life, and my other B&S needed a regrind (and actually could use new piston/cylinder too ) after about 12 years. None ever used leaded petrol.
Sure are.
I don;t think we make that sort of engine anymoe in teh UK.
Tecumseh, Honda, Briggs and Stratton...any more?
Yes and yes.
However motorcycles too were much more 'unleaded aware' long before most cars were here in the UK. My Honda VFR750F bought new in 1996 said to use unleaded for preference. Many car drivers at that time were surprised to see me filling it with unleaded since (compared with most cars) it was a highly tuned, high compression engine.
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