I did the maths on my own shelf last month and stopped enjoying it fairly quickly: four 4-litre drums of used engine oil, a couple of litres of old coolant drained during a radiator flush I never finished, and about ten litres of fuel siphoned out of a Valkyrie that sat through winter storage with a full tank going stale. None of it was going down the drain, obviously, but none of it had anywhere sensible to go either, and it had been quietly accumulating in the corner of the garage for the better part of a year because “I’ll deal with it eventually” is a very easy sentence to keep saying.
A flat-six holds noticeably more oil than most singles or twins — depending on the model you’re looking at roughly 4 to 4.5 litres per full change including the filter — and if you’re doing your own valve adjustments and carb balances on top of oil changes, you’re also generating solvent and degreaser runoff that shouldn’t go anywhere near soil or stormwater. Add a second bike being restored for a club mate, which is how most of us end up with old fuel and old coolant sitting around at the same time, and the volume adds up faster than a single-bike garage would ever produce.
Most Auckland transfer stations will take small quantities of used oil for recycling, usually capped somewhere around 20 litres per visit, and some flatly won’t take fuel or coolant at all because of how they’re classified. Old fuel is the awkward one — it’s flammable and often gets refused by facilities that happily take oil, which means a shed with several litres of degraded fuel sitting in unmarked containers is a genuine fire and vapour risk, not just clutter. I didn’t fully appreciate that until I read the safety data sheet on stale ethanol-blended fuel and realised how much lower its flash point can get as it oxidises.
Ethylene glycol coolant is toxic to animals in fairly small quantities — a couple of hundred millilitres can be enough to poison a cat or a small dog — and it doesn’t break down in a way that makes tipping it on the ground or into a drain remotely acceptable, no matter how diluted it looks. I know at least two people in the club who’ve done exactly that on the assumption it was “basically water,” and it isn’t.
Once you’re past the volume a transfer station will take in one visit, or once fuel and coolant are both involved rather than just oil, the practical answer is a proper collection rather than a series of small trips trying to offload drums a few litres at a time. That’s the point where booking an environmental services contractor made more sense than anything else I tried — one pickup cleared the oil, the coolant and the stale fuel in a single visit, with proper documentation for the fuel disposal that a transfer station wouldn’t have given me anyway, and it meant none of it sat in the garage corner for another six months while I worked out a plan.
I keep separate, clearly labelled containers for oil, coolant and fuel from day one rather than combining anything “to sort out later,” and I’ve set a rough threshold — once any container passes about 15 litres, I book collection rather than letting it climb toward 20 or 25. It’s a small discipline change but it means the workshop never gets back to the point where a corner of it looks like a small hazmat problem waiting to be noticed.
Can I mix old fuel with used oil to reduce the number of containers? No — mixing fuel into oil changes its flash point and can make a load that a recycler would otherwise accept unsafe to transport or process.
Is it legal to just pour small amounts of coolant onto gravel or a garden bed? No, even in small quantities it’s a soil and groundwater contaminant and most regions treat it as hazardous waste regardless of dilution.
How long can old fuel safely sit in a shed before it becomes a real risk? Once fuel has visibly discoloured or smells sour, treat it as degraded — the exact timeline varies with blend and storage temperature, but a year in a warm shed is well past the point of just “topping up and burning it off.”