Old petrol in tank. Drain,drive or top up?

Archeron

Mods. I have posted this in Modified Cars as well, so I hope its okay for me to post here. I'd like opinions from boht quarters if thats okay.


I'm in the process of getting my car back on the road after a period of almost 3 years sitting on its ass and not driving anywhere. I got a new battery, and to my surprise, she started first time yesterday and was ticking over nicely. I let the engine run a bit yesterday to dry it out a bit, and noticed that there is feck all petrol in it at the moment. Now the petrol in it has sat in it for about a year now. I want to get it driving, but as regards the petrol, some people have told me to top it up immediately to stop it running out completely, and others have told me to burn off all the petrol thats in it now (by running the engine) before putting any more in. Does anyone have any opinion as to what is the best thing to do? I really dont want to mess the engine up as its going to cost me a fair few bob to make it roadworthy as it is.

Cheers.

Kimbot

Just put more petrol in it!! If you let it go down too much more dirt is getting into your engine and that will harm it!!
If you top off you will be mixing good and "bad" petrol but in 2 odd fills it will all be gone!!

I remeber hearing on another board this is a bad idea and it should be drained.

Unleaded petrol "goes off" after a month or so. I can't say what will happen to the engine if you run with the stuff you have

crosstownk

I've also heard that petrol goes 'dead' after a period of time. I used to have a car that ran on LPG and if petrol was left unused in the tank for a few months the engine wouldn't run all that well until shortly after I filled up the petrol tank. I'd say fill up with 'fresh' petrol and drive on. The more you fill the more you will dilute the old petrol. I doubt you'll have too any problems.

Archeron

Cool, thanks for the replies all. I'll grab a few fresh gallons and put it in on top of the old.

maidhc

I couldn't start the chainsaw last summer because the petrol was gone off. I spend half a day messing with it until I got the idea of buying fresh petrol, making a new mix... and voila it started.

ianobrien

I'd drain the tank and put in fresh petrol.

Drain the tank by taking off the outlet from the tank and let it flow into a container. If you can't, take the pipe off the carb (that'll tell you how old the car is!).Take the old petrol to the oil recycling centre. Use a lawnmower petrol can to get fresh petrol, put it in and drive to the petrol station to fill it.

I recently put a car back off the road after 2 years of being stuffed into the back of a garage. I did the above with the petrol, but I had to replace the whole braking system. brake pipes (both metal and rubber), brake calipers, rear cylinders, pads, shoes and handbrake cable!

Also, the ignition coil went south, and I think that the head gasket will have to be done soon when I change the valve stems as the valve stems are leaking now and there is a small oil leak from the head gasket.

Don't forget to change the tyres as they have probably perished at this stage and the chance of a blow out is high.

prospect

I'd top it up to the brim with fresh petrol.

Then when the tank is 3/4 full, top it up again.

Kepp topping it up regularly, and you will continually dilute the 'bad' petrol.

craichoe

If the car has a catalytic converter its a bad idea to leave it run dry as it can damage it.

Either

1. Drain the tank and refill
2. Top it up and dilute it as suggested

either will work, might be worth getting the carburetor looked at too, the petrol can turn into a gel in it.

Victor

How the petrol filter?

crosstownk wrote:

I've also heard that petrol goes 'dead' after a period of time. I used to have a car that ran on LPG and if petrol was left unused in the tank for a few months the engine wouldn't run all that well until shortly after I filled up the petrol tank.

You speak as if LPG = petrol.

IrishRover

Not my in my interpretation Victor. He can switch between LPG and petrol. He's saying if he didn't use the petrol for a while it didn't run so well when switching back.

This is a non-issue as far as I'm concerned. The octane rating of petrol can drop after a while apparently, but really, if your car is noticably not running right I'd guess there's other causes like perhaps spark plugs or airfilter or oil needing to be changed, especially if the car has been sat for a while. I really doubt it's a case of having to go through several tankfuls to dilute this "bad" petrol. My money's on putting in a few more litres of petrol and that's any octane issues sorted out.