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AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Mon May 15, 2017 5:01 pm
by AE86

AE86 Tip: ALWAYS use premium fuel on ANY car or truck (petrol of course) that you own.


This is a little bit of a recap on something I've written a while ago but can't find my post on it, but to recap, always run your car or truck with premium fuel REGARDLESS if it is stated as being able to run on regular. Reason being is because the regular fuel in Cambodia often does not meet the minimum octane requirement for more modern cars newer than the early 90's, so knock/pinking and possibly detonation can occur which results in decreased fuel mileage at best and damage to the internals of your engine at worst.

If you use premium, not only will your car be safe from any potential damage, but you will get better fuel mileage and will not end up spending extra money.

***End of summary***

The more detailed and geeky explanation why below.


Okay, three very important things you just need to know to understand why I say what I do.

1. All octane ratings (to the best of my knowledge) are RON octane numbers (research octane). If you are from the U.S. or Canada, forget the numbers you are used to, because they are NOT THE SAME as here. So 91 octane here does not equal 91 octane over there.

2. Most vehicles here are rated for the AKI (R/M+2) octane rating...which is NOT what Cambodia rates their fuels on.

3. RON & AKI (R/M+2) octane ratings DO NOT CORRELATE to one another.

Got it? No? That's okay, it's confusing.


So, what does this have to do with using premium or not?

I know often times people in the West hear about how premium fuel isn't required in vehicles unless specified (like the sticker above states), but for ease of things, just forget that bit of info. Cambodia's octane rating system is completely separate from the AKI (R/M+2) octane ratings the U.S. and Canada (Brasil too) are based on, so none of the numbers apply to what the manufacturers requirements are outlined under. So if the numbers don't apply, then how do we know what we can and can't use? Why not try regular?

Because while the numbers are not related, petrol is still petrol and is designed to be burned in our engines, and even though it's not a hard fast rule...I've found that when using regular in everyday cars, the fuel seemed to "act like" 84-85 octane fuel (U.S. Canada rating). "Normal" cars like a small Kia or Toyota Camry tend to knock on this fuel and get poor fuel economy on it, while motos, even relatively sophisticated ones do just fine, and if you think about it, it makes sense to do this since so many Cambodians use motos on an everyday basis. Why refine fuel more when it's not necessary for a massive chunk of the population?

However, this means that "normal" U.S. and Canadian market cars (which is what most of the cars are here) will not run properly on this type of fuel. So in a nutshell that is why I recommend premium.


Is there any downside to using regular or "street fuel" in a pinch?

Yes, but it's usually not catastrophic. Modern cars are designed to automatically compensate for different conditions, like hot low speed conditions in Cambodia, and can physically run and USUALLY avoid damaging then engine. The trade off is worse fuel economy. However, if your car isn't in the best mechanical condition, or one of it's systems is not correctly functioning, then you may end up causing damage to your engine.


If the regular fuel here is not good enough for "regular" cars, is the premium fuel good enough for cars that require premium?

I can't comment on all vehicles obviously, but I can say that I have a car that requires premium and generates a lot of heat (which makes prime condition for knocking). I've not had a problem with knock related to fuel except on hot days with the air conditioner on while sitting in traffic, then trying to pass a lorry quickly getting on boost. I've also had other cars that have required premium that did not have a problem on Cambodia's premium fuel.

Of course though, mechanical condition has a lot to do with things, so if you do have a problem with knocking/pinking, check to see if your car is okay first.


Is there any advantage to running premium in a moto?

Obviously if you have a "high performance" motorcycle then I recommend only using premium (my high compression Yamaha demands it and does not like regular), but for your average moto it is most definitely not required.

I have heard but haven't confirmed that premium fuel often has a better additives package (meaning extra stuff to help keep the motor happy), but even for a semi complex scooter like a water cooled fuel injected version (i.e. Honda Click, Honda PCX, Honda Air Blade), I've found regular seems to do just fine with no drops in fuel economy and no pinking, even under full throttle loads. It doesn't hurt to try though.

One thing I have found is that my old 2 stroke WOULD NOT START on regular for whatever reason, so if you have problems with an old 2 stroke running smoothly that may be your reason.


Anything else?

I'd personally watch for rural filling stations, not just because of "fast count" pumps (meaning they charge you more than what you've bought), but also because fuel might be suspect also. Plan ahead if you're going long distance and fillup when you can at a reputable station like Total, Caltex. I personally use only Total and Caltex, of course other stations might be fine too, I just have no experience with them.

Alright, stay safe and happy motoring


Re: AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Mon May 15, 2017 9:08 pm
by StroppyChops
Great post.

Re: AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Mon May 15, 2017 9:19 pm
by SinnSisamouth
does the octane rating drop over time?
so if u stick $10 of premium fuel and use it over a two month period does it degrade?

Re: AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Tue May 16, 2017 11:28 am
by Fourkinnel
I've bought bad gas in Cambodia more than once!. One was from Total and the other time I can recall was Caltex. The moto was a XR 250. It got me home but refused to start again until I drained the tank and got some gas from elsewhere. Took a while to sus it out, got a spark at plug and gas getting to it. The fuel looked the right colour, it was the higher octane one (i never use 91 grade) It didn't have that gas smell we all recognise, the smell that indicates potency, that sends your eyes watery, but more like a cleaning fluid. When I was in the motor trade we used to wash oily car parts in a big tank, it sort of smelt like this, maybe paraffin and degreasing agents. Thats all it was good for, cleaning my motorbike. I'm just glad it wasn't a car and I'd just filled the tank.

Re: AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Tue May 16, 2017 12:03 pm
by AE86
I've had so many bad fuel experiences in Cambodia, one ruined our pickup (someone had filled the diesel tank with petrol at a Tela), not just filled our diesel truck with petrol, but actually filled the filling station's diesel underground tank with petrol. I've also had someone fill my moto with diesel, had fast count pumps from Sokimex...just a part of life here honestly.

Re: SinnSisamouth, octane rating does decrease over time, and it's complicated to explain why. In short though for long term storage, best thing to do is to fill a tank to the brim to prevent condensation and oxidation of the fuel (since there is little oxygen/free air in the tank).

Re: AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Tue May 16, 2017 12:49 pm
by SinnSisamouth
i can not afford a full tank ffs!

they used to add petrol to diesel tanks to stop them freezing

Re: AE86 Tip: Use Premium Fuel for Any Car or Truck in Cambodia

Posted: Tue May 16, 2017 9:03 pm
by StroppyChops
My 1999 XR650L went mental when I gave it high-octane fuel. It took a more sensible head than mine to remind me that older bikes won't handle higher octane fuels. Definitely notice the economy difference when I put premium fuel in the 250cc Chinese tuk-tuk though, runs cleaner, less losses of ignition, but more backfires on the down side of bridges. The 150cc tuk-tuk really doesn't care either way, it just does it's thing.