View Full Version : Car fuel octane and cambelt

08-07-2008, 02:43 PM
I've been gifted a car from my older brother and I'm wondering... what octane fuel and when should the cambelt be changed?

It's a 1994 Toyota Camry v6 (NZ new) with 180k kms.

My bro hasn't got a clue and has been using low-octane unleaded fuel, and can't recall whether or not he had the belt/s changed - he got it with approx 75K km's on the clock. There's noise coming from the cambelt area, but it may also be the radiator fan which seems to be spinning at much lower speeds than what I'd expect.

I need to drive it to Auckland and back at least twice over the next couple of months, and given my previously discussed circumstances, I ain't flush with cash.

Thx for any insights.

08-07-2008, 02:50 PM
The techs say that you change the belt every 60,000 miles or 96,560.64 km.

If the engine is an interference design and it should break..there is no way to avoid serious engine damage.

Some of the Korean garbage breaks belts (and camshafts) at 40,000 miles or 64,373.76 km. The damage is total. Love those K-cars.

As to octane, I guess NZ has some obscure way of rating their fuel..so in the US, ALL engines usually use 87 R+M/2 octane and it may not hold water in your place.

PS: There should be NO sounds from the cam cover! A bad and fracturing belt might slap around a short time before it breaks...and the bearings on the tensioner and idlers are not supposed to squeal or rumble either.

ANY noise is an untoward indicator.

And..the fan may not run at full speed if the engine is warmed up and the heat does not engage the fluid clutch in the fan hub. Toss that info out if the fan is electric.

08-07-2008, 02:57 PM
Cambelt replacements seem to vary between 60 000K and 100 000k. 91 Octane is OK.
If you don't know when the cam belt was last replaced I'd suggest you get it done as the potential for major damage if it breaks is high.

08-07-2008, 02:58 PM
Cambelt definitely not more than 100,000 km. Again, if you don't know get it done, at the risk of a rooted engine. You can't afford not to. If you took it to a garage, they may be able to see roughly when it was last done.

Run it on 95.

If you want to muck around with seeing how many km you get per tank with which octane, etc etc, go for it, but 95 will be a lot more economic than 91.

08-07-2008, 04:54 PM
Have a look under the hood, sometimes a date and KM has been twinked on to the airfilter box or the underside of the bonnet.
If it needs to be replaced make sure you get the water pump done at the same time. If you don't the water pump will die a week later.

08-07-2008, 05:24 PM
Have a look under the hood, sometimes a date and KM has been twinked on to the airfilter box or the underside of the bonnet.
If it needs to be replaced make sure you get the water pump done at the same time. If you don't the water pump will die a week later.

Not being sure which engine he has...I'd check first. Some belts don't use the water pump in the system for running the belt..and it might just be an unnecessary and additional expense.

If it's any part of the cam-Gilmer belt system, then absolutely replace it...it's the best kinda insurance against pump and belt failure...

08-07-2008, 05:26 PM
Re the Fan. It could have a "viscous fan", which have a type of wax in them that allows the fan to spin slowly whilst it is cool. You can check this by waiting till the car is turned off and see if you can turn the fan. If you can then it is one of these.

smithie 38
08-07-2008, 06:40 PM
I purchased a 1999 V6 3 years ago and I emailed Toyota and asked their Customer Dialogue Centre the exact same questions you have asked. For my model they replied -

"We can confirm the recommended fuel for your vehicle is 91 octane; the use of a higher octane is a customer preference and will have no adverse effects on the engine. The recommended replacement time for the cambelt is 150,000 kilometres or 10 years (whichever occurs first)."

As a matter of interest I use 95 octane and if you can afford it the car runs better still on 98 octane.

10-07-2008, 01:38 AM
That could be the model where the radiator-mounted fan is driven hydraulically from the power steering pump, and will spin slowly when idling.
I would recommend immediate investigation of noises from cambelt area, before it breaks and destroys the engine, you will most likely need (at that milage) cam and crank seals, idler wheel, tensioner wheel, auto tensioner (small hydraulic ram that acts on the tensioner wheel, may be able to re-use the old one if its not leaking), cambelt and waterpump (is driven by cambelt); this will be fairly expensive but it wont need to be done for another 100,000Km. Dont drive it any further until you get it done.
Higher octane fuel will give more power and better fuel economy.

10-07-2008, 04:48 AM
The US Gummermint has posted some advisories on fuel octane and the associated myths about it.

Typically, if you are talking vastly inferior products and/or non-scientific and illegitimate posted values involving fraud to the consumer, then all this may fly out the window. I am suspicious that NZ has this problem because of the sheer number of anecdotal evidences presented here in this forum in the past.

The report follows:

When it comes to the grade of gasoline or octane rating your put in your car, "More is Better" right?

Not always. There are a number of myths surrounding the use of high octane gas.

Myth #1 - Using high octane gas will make my car perform better.

Not exactly. If your car is "pinging" or "knocking", a higher octane gas will help or eliminate the ping and save your engine, but it does not directly add horsepower. However, it does keep your electronic ignition from retarding the timing as an "anti-knock" measure when pinging is detected.

There may be mechanical reasons for your engine pinging too. This may be caused by incorrectly set timing of the camshaft from a poorly done cambelt replacement or a repair to the head(s) that removed too much material from the gasket area, resulting in greatly increased compression ratios.

Myth #2 - My car will get more Miles Per Gallon by using a higher octane gas.

Since a higher octane gas does not produce more power and is actually a flame retardant, you will not get better gas mileage.

Myth #3 - My engine will run cleaner and produce less emissions and smog with a higher octane gas.

Not true. Many oil companies advertising methods may lead you to believe this, but octane has nothing to do with how "clean" your engine runs.

In fact, the direct opposite may be true if the catalytic converter becomes overheated from the plasma-like exhaust gasses still burning when they hit the matrix and rare earth chemicals in the converter rendering the matrix into a molten and non-functioning blob of slurry.

Myth #4 - Octane is added to gasoline to produce a higher quality fuel.

No, actually Octane is the gasoline, at least most of it. See Octane Rating below.

You can save money on gas simply by using the lowest octane rated gasoline that your car will tolerate. Using a higher octane gas than what the manufacture states is simply a waste of money. If you are not sure what octane your car is designed to use, you can start with the lowest octane gas (87 in most areas) and try it. If it pings under load, then move up to the next octane and only purchase the lowest octane grade that your car needs. There may also be mechanical reasons for you particular problem too. For more information on octane, read on.

What is "Pinging" or "Knocking"?

Most of us have heard the rattling noise from under the hood, usually when the engine is under extra load like climbing a hill, towing a boat, or in a loaded truck. The noise itself is caused when the air fuel mixture in the
compression chamber ignites too soon (pre-ignition or detonation).

This condition causes the air fuel mixture to burn unevenly and
produces the ping or knock sound. This uneven burn causes flash points in the combustion chamber and can lead to engine damage.

What Does Octane Do?

Without getting into all of the chemical properties and technical stuff, basically octane raises the combustion point of gasoline when under compression and slows the burning. The result is that it makes the gasoline less volatile so that it does not ignite before your ignition system makes it fire at the correct time. The intent of octane is simply to provide a anti-knock property.

Octane Rating Guidelines

The Octane Rating you see at the gas pump is simply a percentage of the Octane-Inducing Chemical in the gasoline mixture. In other words, if you purchase gas with a 87 Octane rating, that mix contains 87% Octane and the remainder is lower quality chemicals like heptane, pentane, cetane. Also see http://en.wikipedia.org/wiki/Octane_rating

I have personally repaired engines that were illogically and habitually run on higher octane fuels because of the owner's brainwashed Madison Avenue training that higher octane was somehow better and more power-inducing and a treat for their engine like a yummy doggy biscuit for your pet.

The slower-burning fuel actually induced intense heat and warpage to the exhaust valves as the still burning gasses passed by the exhaust valves; in some cases the valves got so hot they melted and chunks of or the whole valve face dropped into the combustion chamber and destroyed the engine.

For fuel to perform and render the most effective power to the pistons, it must be fully consumed by burning and expansion in the combustion chamber, not still burning and dumped out the exhaust.

My stand is this: in a properly tuned and functioning engine, higher octane or premium fuel is a waste of money and provides no additional performance (power, emissions and/or mpg). In fact, it may mean a slight reduction in performance and a real chance of engine damage if used constantly or under periods of high performance and demanding power requirements.

Iíve listed a just a FEW of the websites that I came across providing information on my position, with the facts that follow.




sam m
10-07-2008, 08:00 AM
180k means only 2 things. It is way way overdue or it is going to be due in about 20k. Do it. If you suspect that it is way overdue then you are probably looking at new tensioner and idler bearings as well. Investigate packages that include everything to save money. Dont dismiss ringing Toyota dealers for parts as well - I have been surprised a few times about their prices occassionaly beating aftermarket part prices.

Also I like the suggestion to replace the waterpump - if it is cambelt driven of course. This then introduces a few more costs but spending dollars like this on a toyota is money well spent.