premium 95 RON not enough?

[robert112]

Hi all,
New owner of an auto 97 prelude vti-r.

Check engine light came on the other day so I took it to hanny's to get the code pulled and it came across as code 23 - knock sensor.

He asked me what petrol I poured in and I said premium 95. Pete says that that's why and that this car needs premium 98.

Is this true? I didn't even put 98 in my s2000 and it never did this..

[DLO01]

What does the book say to use?

It definatly would not say 98, unless its has some mods or tunned on 98.

[NSPYRE]

prelude is rated at 95 RON. how very odd it should do this... could be shoddy fuel... could you hear your car pinging?

[krogoth]

^yeh, werd u get ur fuel from?

and how long have u been hearing pinging for?

[robert112]

I can't hear or feel pinging. it happened while cruising at 90km/hr on the m4
I got my fuel from Mobil.

I don't know what the book says to use as I don't have it.

[robert112]

I'm also getting poor fuel consumption. 300km a tank with conservative driving (although its an auto)
I wonder if this is related.

[honda-prelude]

Hey mate, i drive a 1997 Prelude Vtir, and mine has clearly stated on the inside of the petrol cap/lid in white bold writing, PREMIUM FUEL ONLY... check yours when you have the time, the previous owner may have removed the sticker though...

[aaronng]

Did you have any work done on your engine recently? Someone might have knocked the knock sensor loose or damaged it.

[omgzilla]

I only run 98 octane in my VTi-R EK4.

Have you been using ethanol blended fuel?

My parents have had alot of trouble with power loss and pre-ignition with the ethanol fuel in their cars.

I'd keep clear of it in anything other than a Holden/Ford/Mitsubishi family car.

[aaronng]

^^ He said he gets his fuel from Mobil, which don't sell ethanol blended fuel (yet).

[NSPYRE]

just because it says code 23 for knock sensor does not neccesarily mean that your car is pinging. you say u CANT hear pinging so as aarong said, could be something wrong with the sensor itself

[EuroDude]

Perhaps some water was pumped from Mobil into your tank?

When was the last time you adjusted the Valve Tappets?

[robert112]

Hey mate, i drive a 1997 Prelude Vtir, and mine has clearly stated on the inside of the petrol cap/lid in white bold writing, PREMIUM FUEL ONLY... check yours when you have the time, the previous owner may have removed the sticker though...

hey mate, but that doesn't necessarily say put in 98RON does it? The pumps label 95 as "premium"

aaron: no work mate, i just picked up the car last week and is stock as a rock.

anyway dont worry guys the problem hasn't come back in 200kms of driving so far....

as for poor fuel consumption the previous owner used 20w 50w grade oil so im going to do a changne tomorrow to 10 30 and see how that goes. I was told that would be the cause of poor fuel economy.

I'll let you know how the fuel issue goes in a couple days.

[aaronng]

hey mate, but that doesn't necessarily say put in 98RON does it? The pumps label 95 as "premium"

aaron: no work mate, i just picked up the car last week and is stock as a rock.

anyway dont worry guys the problem hasn't come back in 200kms of driving so far....

as for poor fuel consumption the previous owner used 20w 50w grade oil so im going to do a changne tomorrow to 10 30 and see how that goes. I was told that would be the cause of poor fuel economy.

I'll let you know how the fuel issue goes in a couple days.
If you just picked the car up, you should do a full fluid change. Since it has 20w-50 in it, don't go to 10w-30. Use a 10w-40 instead. Also, change your transmission fluid, brake and clutch fluids. If the coolant has not been changed by the previous owner recently, replace that too with Honda coolant. If the fuel filter hasn't been changed or the air filter is dirty, replace them too.

[robert112]

yep, its going in for a major tomorrow. as for using 10-40w that seems to be the general consensus on the net but every mechanic ive spoken too seems to say 10 30 even tho their aware of the kms the car has done... i wonder why they say stick to 10 30 rather than go to 10 40?

The way I see it is 10 40 being slightly thicker might be better for larger clearances on older engines and would end up having to top up less but the money saved in toping up less is probably spent in filling up more petrol ... since thinner oil gives greater fuel economy + power..

duno, just rambling on.. just my thouoghts.

[aaronng]

10w-30 is the specced viscosity for the oil of a new Honda engine. If you are confident that your engine is not worn to larger clearances, then 10w-30 is fine. But since you do not know the history of the engine and it has been using 20w-50, going down 2 steps is asking for trouble. Why go for 10w-30 and then having to put the car in the workshop to fix up problems when you can step down 1 step to 10w-40 which is already very good even with regards to power and fuel consumption? The difference in power between 10w-30 and 10w-40 is not worth the headaches that you risk getting if you experience problems because the oil is too thin.

Just use 10w-40 for this oil change and if you don't experience consumption, then go to 10w-30 for the next oil change. It's not like you are just keeping the car for 6 months and have to use 10w-30.

[robert112]

aaronng, i can see where your coming from and i do admit it makes sense.
the points that i argue would be
1. several reputable mechanics (i wont name names without asking permission) have said 10 30 even tho their aware of the cars kms. i haven't questioned why tho
2. if you have 10 30 and 10 40 in a car thats in bad condition it's going to leak oil on both those grades anyway... AND... a thicker oil may not get burned up as quick BUT will not travel to tighter areas for lubrication.

in any case i'm not disagreeing with you just thought it's an interesting topic.

I put in 10 30 and i'm keeping an eye on it over the next few days so far so good tho no signs of oil being burnt up.

on another note my knock sensor code came up again =( Looks like im out of pocket $350~ to get it replaced =(

[aaronng]

1. I'm sure the mechanics have their reasons. So you should ask them why.
2. It's not leaking now with 20w-50 isn't it? 1 step down at a time is better commonsense than 2 steps at a go. You're not going to save much money in terms of fuel consumption between 10w-30 and 10w-40 anyway.

In the end, all I'm offering is advice. You don't have to follow it. If you don't find oil consumption with 10w-30 and all is fine and good, please post it up here so that I know that I was wrong. :)

[robert112]

yea I will ask them next time and see what they say.

I think you mis read my last post, I already put in 10 30 for 2 days now and it's been running great with no signs of oil consumption so far.

I'm greatful for the advice =] The only reason why there was 20 50 was because the motor was low on oil when i went to test drive it and I'd rather him put in the only oil he had around (20 50 for a diff car) and to have it topped up with a litre of it rather then test drive the car while low on fuel, it wasn't using 20 50 already or anything like that.

[aaronng]

Ahh, I see. Do you know what was in the engine before being topped up with 20w-50? If it was 10w-30, then the mixture could be close to a 15w-40. Also, you did a full drain and changed the oil filter when you put 10w-30? Keep monitoring every week over 1000km to see if the level goes down.