Articles of Interest
Petrol and oil for paramotors
written by Keith Pickersgill 4 January 2008
Too many paramotors of all brands are brought to me for repairs after suffering damage as a result of incorrect petrol or oil being used. I seem to be repeating the same advice over and over again, so now I am writing this article in the hope that this will save you, the paramotor pilot, some expensive engine damage.
We shall cover three aspects, (1) Petrol (2) Oil and, (3) mixing of these:
The ideal petrol is the old-style petrol containing the metal lead, but that is no longer available in most of South Africa.
In the absence of leaded petrol you should use unleaded petrol, of the highest Octane available in your region.
NB! - LRP or "Lead Replacement Petrol" should NOT be used for any paramotor!
In a pinch, you could also use AVGAS, though it is more expensive than petrol. There are no real benefits to using AVGAS except the higher Octane value which could reduce pinging on engines that have been too highly tuned.
In the forestry regions of South Africa (Garden route, KZN, etc), many chainsaw shops sell BP Special Premix Two-Stroke Fuel which is excellent and does not require any oil to be added. It can be stored in sealed metal containers or special high-pressure plastic containers for extended periods of time without any degradation of quality. Specially developed by Stellenbosch University for the local forestry industry, this has already saved millions in maintenance and repairs. Unfortunately it is not widely available in SA so should be avoided unless you take effort to only use this fuel and carry sufficient stocks wherever you travel. You cannot change back and forth between this and ordinary petrol/oil mix.
Use only the very best quality 100% fully synthetic two-stroke oil, and stick with one brand. You should not change oils unless you have absolutely no option.
We recommend any of the Castol products, of which there are currently a few different products, however these are all fully compatible with one another and can be changed between, or even mixed in the same tankful.
These Castrol products are:
- Castrol TTS - might not always be readily available
- Castrol R2 Enduro - newer product, developed in SA and exceptionally good
- Castrol Power One Racing 2T - the latest product, being introduced worldwide
- Castrol Power One TTS 2T - equivalent to the original TTS
Should you choose to use a different brand, ensure it is 100% fully synthetic.
Pricing could act as a guide too, with good synthetic oils costing around R100 per liter as at January 2008, whereas the minerals are around R40 a liter and the semi-synthetics somewhere between this range.
Some pilots deliberately opt for the cheaper two-stroke oils and in many cases, are using outboard oil which is quite likely the very worst option.
Why is outboard oil so bad for paramotors?
Because outboard engines run at very low temperatures and usually have an unlimited supply of water to keep them cool (drawn from the water under the hull of the boat). Paramotors run at far higher temperatures and usually have higher compression ratios as well. Even if your paramotor is liquid cooled, I bet it has no coolant pump and relies purely on thermodynamics to circulate the coolant, and I bet it carries a miniscule quantity of coolant. In short, outboard oils cannot handle the punishment dealt out by modern paramotors. Not even the "Super Outboard Plus" oil which is in wide use (or misuse or abuse).
The money you save now on oil, you will spend many times over on repairs if you skimp on the oil. Find out what a replacement crankshaft for your paramotor costs (you may need a tranquilizer when you hear the cost!). Remember that if you damage the conrod or big-end bearing, you will probably need to replace the entire crankshaft with conrod and bearing!
- Mixing Fuel.
Once you have mixed your petrol and synthetic oil, try to use it up within a week or less. Petrol is a complex blend of many chemical compounds and some of these gradually react with synthetic oil. Most paramotor manufacturers insist that you discard mixed fuel/oil after 4 days or even less, however if you have some fuel remaining after Sunday's flight, you must try to use it up the next weekend, otherwise you must take it out of your paramotor's tank. The best way to discard mixed fuel/oil is to add it into the fuel tank of a petrol-engined car that is NOT fitted with a catalytic convertor. If the car has a catalytic convertor, the oil will destroy it very quickly!
Do not try to mix the fuel & oil in your paramotor's fuel tank. Instead, use a small jerry can to mix your fuel and oil, then use a syphon or funnel to transfer some mixed fuel to your paramotor tank. We usually mix Ten liters at a time, as that is a typical weekend's requirements (approx 3 to 4 hours flying). First put the oil into the jerry-can, then the petrol! This ensures it is mixed thoroughly.
It is easy to figure out the quantity of oil required for ten liters of fuel. A mixture ratio of 40:1 is the same as 2.5% and in 10 liters of petrol, that is 250ml of oil. A ratio of 50:1 is 2% or 200ml oil in 10 liters petrol.
It is not easy to pour an exact amount out of an oil bottle, even if it is clearly calibrated. It is far easier to pour an exact amount into another calibrated bottle! i.e. better to have the calibrations on the bottle you are pouring into, rather than out of. So first pour into a calibrated bottle, then empty that into your jerry can. The smaller the diameter of the bottle, the further apart are the calibration marks, the more accurately you can measure your oil.
A 250ml baby's bottle is an ideal measuring bottle, as it is pre-calibrated, is clear in colour, is strong and durable and can be safely carried in your paramotor harness for re-fuelling en-route on cross-country flights. If your ground-crew bring your fuel to your stopover field, then refuel from your pre-mixed jerry-can. If you are purchasing clean petrol at a garage or airfield or boat-shop nearby your landing field before continuing the cross-country flight, this is the only time you should permit mixing of fuel and oil directly into your paramotor's fuel tank (again, first pour the oil in, then the petrol).
Makro and many outdoor shops sell a perfect Ten Liter metal jerry can. They also sell a super-syphon which self-primes just by shaking the end that is in the supply tank (no need to suck on the hose with your mouth!).
Consider adding a large diameter fuel-filter to your syphon. Inspect the inside of your tank and jerry-can regularly. If there is much debris inside, take the effort to clean it out as often as required (usually every 10 flights or so).
If in doubt, ask a reputable instructor or dealer for advice.
Address comment to Keith Pickersgill at firstname.lastname@example.org