Fuel concern after theft
 

My modified WRX was stolen and recovered after a couple of weeks.
The felons would have topped up the fuel during the period they had the car.
Unlikely utimate 98 would have been used.
I want to dump all the old fuel and get a new tank of ultimate or alternatively chuck in 10 litres of toulene then top up with ultimate.
Any comments?

Check the bottom of the tank for drain plugs. My Forester has a drain on each side of the tank.

What year/model is it. Betty's 2008-2014 have no drain plug for the fuel tank.

It is a MY99

I would put in a tube of octane booster and top up the tank with as much 98 as you can.

How much fuel is currently in the tank??

I wouldn’t even question dumping it. What’s a tank of fuel worth versus the knowledge of what’s in it isn’t going to ping?

Who even steals a car and [I]doesnt[/I] trash it and crash it. Let alone fill 'er up.

Drain all fuel from tank.
That fuel can be used in the shopping trolley.
If you have a can, buy a few litres of 98.
Drive at low revs and boost until after your next fill with 98.

If you can't do all that, drain or syphon out as much as possible of existing fuel.
Use octane booster up to double recommended amount is ok.
(it may not mix completely, too much is not seriously harmful).
Drive at low boost and revs until your second fill with 98.