Does anyone on the forum use Shell Optimax, the reason I am asking is I was doing a trial on it ( on recommendation) to see if the kombi runs any better, and it does BUT I have found it is stuffing the seal on the fuel cap which now leaks, and now the fuel pump is leaking ? , coincedence or what

I think it could be coincidence, or the pump was only being held together by crud and the optimax cleaned it out. The seal could already have gone. How old was the cap? Did petrol get on it directly?
I have only used Optimax in the GTI since I owned it, and while it is not aircooled (cannot vouch 100% for those engines)it was a UK model from 1985 and therefore leaded, and the fuel has improved the performance and increased the mileage. I have never had an issue with rubber seals and optimax. Good luck an I hope this helps...

Likewise, I have used it for a while in Andy, and no leaks. Mind you everything (fuel line/fuel pump etc) are also fairly new.
:thumb

Did some testing a while back comparing Optimax with Pulp and we felt that the car (1200 F-Vee) did not perform nearly as well on the optimax.

As an aside, A given engine combination will produce higher horsepower on the lowest octane fuel it will tolerate.
I happily run plain old low octane ULP in the race car.
L8tr
E

Dudes.
Optimax is no good on any older cars using carbies.
I work for shell and after stuffing a bettle motor using optimax, i was told at a seminar that Optimax was no good to use on older motors on a regular basis.
Make sure you use the valve master when using optimax.
If you are using it just for the octane rating ,just use the octane boost products out there with your regular fuel

Octane ratings has almost nothing to do with power output, heat output or anything like that.

A higher octane fuel will burn slower and more evenly than a low octane fuel.

Newer engines work better with higher octane fuels due to their combustion chamber design.

Engines with high compression ration (> 9.5:1) with ECUs and fuel injection can use high octane fuels and are likely to have fuel maps for the higher octane fuel. Most Euro engines do not have a fuel map for 91 fuel and require a minimum of 95 fuel relatively low sulphur (< 100 ppm) fuel (which is the minimum you can get over there). They use "limp home" mode when they experience too much pinking or unacceptable emissions which is why for watercooled owners, you should stick with 95 or better fuel. These engines will feel slow or gutless using the "limp home" mode.

Older engines with low compression ratios (say the 7 to 8:1 of most non-race non-aero aircooled engines) don't make use of these modern techniques because they are retro tech (see pictures from the EPA Car Ecometer, relating to my two cars, with my driving habits and distance) and have terrible emissions as a result. Therefore, as long as you don't pink or backfire on the lowest cost fuel you can afford, you can't hurt the environment much more than about 30 odd new cars.

Optimax is a good fuel - it's low sulphur (50 ppm), has cleaning agents, and generally will make modern engines use a little less fuel and feel peppier (certainly did on my previous three cars, haven't run my Cit on anything else yet).

The old "Super" was 96 RON, but if your engine can handle the normal 91 RON fuel without backfiring, go for it.

Andrew

I use B.P ultimate in my Beetle and XR8.
Ultimate is simular to Optimax, anyway my Beetle seems to run the same wether it has LOW or HIGH Octane fuel.
But my XR8 seems to go about 5-10 % better on HIGH OCTANE.

I saw a V8 2000 model Ford go on a Dyno, with a tank full of low Octane fuel and it PINGED it's guts out.

I run Optimax in my 1800 kombi, because it noticably decreases pinging, allowing me to run a few degrees of extra advance.

I was running Optimax in the 1500 Beetle also, but Heather chooses to use standard ULP, so I've since timed it accordingly.

I'm not sure about the seals thingy, but I believe I get more oomph from PULP. :thumb

Well at just over 92,000 MILES since putting TOYBUG together 4 years ago I have run with Optimax almost in every tank full
And for those who have cruised with me you know it goes
the differences is about 45 miles better per tank than ulp
so the cost is ruffly the same I had the heads of in Nov and they were spotless
have not found any seals to have perished (I have no cork seals)
In the Kombi it gives much better grunt than ulp

Dougie

Dooood!
I know what I know.
As a former fuels and lubricants rep for a Caltex, I have good access to the fuels info I need.
Furthermore, I have been building, racing and tuning HiPo 2 stroke road race engines for nearly 20 years.
I can tell you that for a GIVEN setup, it CAN be made to produce MORE hp on the lowest octane rated fuel the given setup will cope with but at the expense of grenading unless EVERYTHING is absolutely correct.
CMS performance in melbourne are noted Honda GB Bike 2 stroke tuners and their title winning RS125 Hondas are producing the most hp they have seen on plain old pump ULP! This is the vicinity of 380 BHP/Litre.
Because they can!
They dont bother with high octane jungle juices and boutique race fuels. Pump ULP, however, and this is a bit however, they stress the propensity of the engines to grenade.

I dont think you are quite getting the point of my post.
Oh well.
Pity I cannot find my data and sources.
You loose that stuff when puters die!!!!! Phttt!

L8tr dude
E

Guys this might raise a few eyebrows.
In NSW their has been 9 proven cases and another 23 current court cases to do with optimax against shell australia .
All cases are engine damage related.
Not all high millage old cars either.
one case is a 03 subaru wrx with 11,624kms on it .
If your going to use a high oct fuel go the BP Ultimate

my 2 cents worth. i run ulp in both my fastback and KG , both set to 32 degrees advance with no problem. in the 1800 kombi with hi comp heads i need to run pulp but usually use caltex pulp since it is about 5 cents a litre cheaper than BP or Shell .

Hey 0064
Whats the gist of their claims dude?
L8tr
E

ya got U2U Tassupervee

My ECU'd knock-sensored car pings like **** on Opticrap, but kicks butt on BP Ultimate. I don't think Optimax is as good a brew as it was when launched. As for using it in air cooleds, I don't know!

I tried optimax on the weekend just to see what it was like
have to say I agree with VWcool mine pinged is heads off when tanks was nearly empty ( eedle hanging of guage) filled with Bp ultimate and the pings are gone going to stay with BP ultimate thats for my car each car and setup is different

Marc

well I use optimax in the bug and it seems OK :thumb. Have not tried BP ultimate so I can not compare.

Not as cool running as BP100, about 5-10 deg C diff, on the track. But then you can't buy bp100 or Avgas from the local servo either unless you want to pay $50 for a 20lt drum!!!

Nope and you cant buy it without a Govt. passbook now.
Fines for running the stuff in a vehicle not in motorsport start at (from memory) $50,000 bucks for an individual and a lot more for companies.
Furthermore, you wont ever be able to buy leaded Avgas after March 2005

Have fun!
L8tr
E