unleaded 95 and 97???

i usuaully use the standard unleaded (95) when filling up but the petrol station was out of it today so i decided to go for a tank of the 97 variety... but what's the difference? i can't really feel any when driving. also, is it ok to mix the two? because i had a tiny amount of 95 still in the tank before filling up.

also, probably unconnected but my engine randomly became really hot this evening (after an hour or so of being in slow moving traffic) and came up with that stop sign, even though i was more or less in a standstill. i did stop somewhere and it went.. (smelt burning for a second before hand); what kind of things cause this?

Reply 1

tranquil_rage

I'm not sure about the heat and burning smell but I can explain the numbers for you.

They are the "ron" rating of the fuel. A higher rating means a higher octane content. Higher octane contents are useful when tuning an engine. A highly strung engine can sometimes detonate with low octane petrol. Engines normally burn the fuel/air mix in the chamber evenly. It spreads out from the spark plug and ripples downwards into the piston head pushing it down to create the drive. Detonation is when the fuel/air mix doesn't burn but explodes. Having a higher octane rated fuel can help stop detonation.

Unless you ride a sports bike or drive a fast car it will make no noticable difference. However it wont hurt either.

In regards to the overheating have you checked your water level? Also make sure nothing is obstructing the radiator (its easy for plastic bags and leaves to clog them up in some car designs).

Reply 2

silence

oo interesting. it doesn't sound like it'll help my 1.2 engine that much then. i asked about the overheating thing in case it could be linked with the new petrol, but i guess it must have been a small obstacle, and it just randomly disappeared when i did a reverse manoeuvre.

another interesting thing today; when parked down a sidestreet to watch fireworks, i'd just stopped the car and there was this other family watching from their car. then they got out and started playing with sparklers right behind my car. i don't know if i was being pedantic but i got out the car and told them it wasn't the best idea to play with a sparkler next to a car's exhaust pipe.. some people.

Reply 3

tranquil_rage

As a side not its no danger to put burning things near an exhaust. If there was anything that would catch fire there it would have caught fire long ago from the insane heat an exhaust kicks out by itself. :smile:

Reply 4

recneps

tranquil_rage

True. However, if they were waving sparklers around behind my car I'd still ask them to move - as it sounds like a recipe for damage to the paintwork.

Reply 5

Kingspharm

With good quality super unleaded (97 octane) you can get some performance boost, my engine runs better with that instead of normal 95. Insane price difference though for the good stuff.

Usually will say in the car's manual if it's OK for you to use either 'strength' of fuel.

You can get octane boosters in Halfords, etc. as well which can boost the octane level of your fuel by something like 5ron.

Reply 6

snmichaels

I agree with the first response about the higher ocatane rating. Cars with advanced ignition timing(a little complex), turbo, supercharged and nitroused (not all at the same time) are meant to use higher octane petrol. You can get a larger safe window for tuning with it. Hence race petrol can use 114 or more. It's to prevent detonation ("Pinging").

As for the overheating, it's nothing to do with the 97. Sitting in traffic puts a huge strain on your cooling system. The main reason is because you're not moving enough air through the engine bay. Road wind plays an important role in cooling the engine. These front wheel drive cars have usually small little electric fans that have a hard time moving enough air. They're usually okay if your cooling system is in good working order, but if one element is not functioning properly, sitting traffic will cause a problem.

Considering that it isn't hot outside anymore, there might be something wrong somewhere, it shouldn't overheat in these temperatures.

The first thing to check is if there are any large leafs stuck to your radiator. This is autumn so it's a possibility. Then check the water levels. These two things are the most likely and don't really cost anything to mend.

If you're still having trouble, let your car sit, running, for about 15-20 minutes. Then have a look under the bonnet and see if your fans are coming on. You can also listen out for this if you know what they sound like. If your car starts to over heat and the fans aren't coming on, check the fuses first. If the fuses are fine, then maybe it's the fans. These are pretty easy to swap, as they're just screwed to the back of the radiator and plugged in with a little plastic electric clip.

If there is still a problem, the next thing is to have the raditaor flushed, this needs to be done at a shop/garage. It might be clogged up with something. Then have the water pump replaced. This is a little more complex to replace so probably have a garage do it.

Also have a look at the thermostat. I'm not sure about all cars, but for some, they're located somewhere between the radiator and the water pump. They basically open or close at certain temperatures. They close when you first start the car and it needs to warm up. Once at normal operating temperature, they open and allow water to flow through they system. If they are stuck closed, it won't allow water to flow through the radiator and the car will over heat. These are very cheap to buy and aren't too difficult to replace.

These are the only things I can think of that might be the problem. Hope this was of some help.

Reply 7

sanelunatic

My car pinks on 95 octane fuel, I think that is perhaps more to do with the timing of the ignition though. :frown:

Reply 8

snmichaels

The timing may need to be adjusted, it shouldn't ping on 95 unless somethings wrong, or it has a lot of engine mods.

Reply 9

sanelunatic

Unfortunately its not the latter. Almost standard 1800cc.

Reply 10

Pookie

silence

another interesting thing today; when parked down a sidestreet to watch fireworks, i'd just stopped the car and there was this other family watching from their car. then they got out and started playing with sparklers right behind my car. i don't know if i was being pedantic but i got out the car and told them it wasn't the best idea to play with a sparkler next to a car's exhaust pipe.. some people.