General Best Petrol Fuel for the Panda 1.2

[Pugglt Auld Jock]

It's a common misconception that high octane fuel is just for high performance cars with high compression engines being driven hard, but that's not always true. The answer's not that simple; it depends, among other things, on how you drive the car.

Modern engine management systems can adjust the ignition timing on the fly to make the best of whatever fuel they're using. At lower rpm, retarding the ignition allows the engine to develop more power and torque (the opposite is true at high rpm); the limiting factor is the preignition point. This is when older cars would 'pink', sometimes causing serious engine damage, but a modern engine will advance the spark to stop this happening. This prevents pinking, but generally it's at the expense of power and economy. Higher octane fuel allows the engine to run more retarded at lower rpm, and this helps both power and economy at the bottom end of the rev range (provided of course that the ECU is sufficiently capable).

If you're the kind of Panda driver who likes to keep below 1800rpm in the intermediate gears, you might get more benefit from a high octane fuel than you might think. The difference is certainly noticeable in my own Panda.

What I'd suggest is that you try a few different fuels and find what works best for you.

higher methanol is bad news for the engine and engine oil
(amongst other things it can degrade its oil lubrication properties thus increasing wear on critical engine parts):

• Contamination
  Methanol and water contamination of lubricating oils can deteriorate their lubricating properties.
  
  
• Poor lubrication
  Methanol has poor lubrication properties, which can increase wear on engine fuel system components.
  
  
• Short-trip driving
  In severe short-trip driving conditions, methanol vehicles can have more fuel and water collect in the oil, which can degrade the oil's protective properties.
  
  
  the ECU/engine management software, no matter how ‘clever’, cannot overcome physics+chemistry​

Here's a different take on this.

Before I bought the Ibiza (2016 95 hp EA211 1 litre turbo petrol engine with direct injection) I had been running my much loved 1999 Seat Cordoba 1.9 tdi, so that's the engine before the PD. Other family vehicles were all pretty "old tech" so I read up a lot about direct injection engines and soon came across the problem with inlet tract carbon fouling. For those not in the know, DI engines inject their fuel directly into the cylinder whereas older indirect (port injected) engines deliver their fuel into the inlet ports. The relevance of that is that port injected engines spray fuel onto the back of the valves whereas DI engines do not and subsequently, on DI engines, the detergents in the fuel can't clean carbon off the back of the valve heads and inlet ports where, over time, it builds up and impairs performance and general running. I know many of us will know this, but thought it was worth mentioning for anyone reading this who didn't.

I discovered a lot of other very interesting stuff about DI engines, like their astronomically high fuel injection pressures etc. but noone seems to have a "cure" for this carbon fouling. I did however come across a fuel additive which made some pretty interesting claims Archoil AR6900-P Max so I got in touch with the supplier and had a series of very interesting conversations with them. Now I want you to understand that I'm generally not in favour of additives per se and in fact, I would never use engine or transmission oil additives - preferring to buy the very highest quality, manufacturer compliant, product I can find. However I think fuel additives which clean and protect with additional lubricating properties - Petrol, unlike diesel, has no inherent lubricating qualities - are an interesting topic and have a contribution to make with regard to keeping injectors spraying nicely. The Archoil: https://www.powerenhancer.co.uk/product/archoil-ar6900-p-max-advanced-petrol-synthesis/ makes many claims but the one that interested me most is that it claims to be able to reduce inlet carbon fouling on DI engines. I started using it in the Ibiza when she was about one year old and used it continuously until I p/x'd her just over a year ago. and I've been using it in the Scala since I bought it so, in total for about 9 years now, adding it in the recommended quantity to every tank of fuel, and there have certainly been no detrimental outcomes. I was about to remove the Ibiza's inlet manifold when her antifreeze change was due at 5 years old so I could examine the inlets but, unfortunately, the gearbox started sounding just very slightly "off" so I didn't do it - The gearbox subsequently destroying a final drive bearing on the M6/M5 resulting in a new box being fitted - ouch! So, disappointingly, I can't report on whether the ports were clean or not, but I can say the engine ran as well when I sold it as when it was bought new.

So, enough about the Ibiza, which I've written about so you understand why I have the P Max, and now to comment on how we fuel Becky, our 2010 1.2 Panda Eco Dynamic (So she's a pre VVT 60 hp). Mrs J would have a fit if I "wasted" money buying premium fuel for Becky when she seems to run very well on the E10 - Mrs J wouldn't notice a slight misfire or increased power due to using E5 though. So we've always run her on E10 and been very content. However, when I started dosing the Ibiza with the P Max I also started adding it to Becky's tank. I decided to do this primarily to help with keeping the injectors, fuel pump, and other components in the fuel system clean and lubricated but, after a while I noticed that she seemed to rather like it. Definitely running and ticking over more smoothly and, possibly pulling slightly more willingly - There's a long hill up from the harbour where this is definitely noticeable. Maybe due to it having cleaned up the injectors?

So, in summation, This additive does seem to be doing some good. I doubt if it can be keeping the inlets on the DI engines "squeaky clean" - without injecting into the ports I don't think that's possible - but I do think something's going on, maybe with gasses drifting about on overlap? and it's probably keeping Becky's inlets so clean you could eat your dinner off them! On both engines I think the additional lubricants are probably doing stuff like fuel pumps - 'specially the HP pump in the DI engines - and injectors some good because being on the "fuel side", it can reach places engine lubricants can't.

Last year I filled the Scala with E5 at our local BP station before departing to Devon and, as I always do, kept a very careful check on fuel consumption. I was thinking I'd see a few miles more for every gallon but no! she got as near as makes no odds, exactly 60 mpg for the whole journey which is exactly what she's done before running on E10. I can't say I noticed any difference in power out on the open road either. The P Max claims to give a small performance increase so maybe that's it? Anyway, we're very happy running E10 and P Max in both vehicles so I think I'll just carry on like that.

Ridiculously perhaps? I run all my horticultural petrol engines on E5 - not for any performance gain but to reduce the impact of the ethanol on the rubber components - fuel pipes, pulse pump diaphragms, float chamber needle valve tips (which are sometimes rubber tipped) and other parts. I should say all my machines are pretty old, being as how classic horticultural machines are part of my hobby activities. I would be surprised if modern garden machines - lawn mowers, cultivators, hedge cutters, etc would be affected though as E10's been around for a while now and even longer in the States for instance where Briggs and Stratton and other manufacturers are based. I'd take a bet that Chinese made stuff is tolerant too?

So, a wee bit of a different take on E10 fuel? but seems to work for us. I guess the E10 with P Max added probably works out pricewise around the same as E5? but I like the idea of the possibility that I'm gaining protection for the various components in the fuel system. Who knows though, maybe I'm just chucking my money away? Doing it with a smile on my face though!

 

[Herts Hillhopper]

So your saying stick with standard unleaded fuel?

Sorry - been busy...

Basically, yes.

But, with a caveat. The so called 'premium' fuels are different for three reasons: yes, they have a slightly higher octane rating; also they contain less ethanol (5% rather than 10%... those E5 and E10 numbers) which in turn makes them more 'stable' and less prone to absorbing water from the air; and thirdly (and this is likely the reason many feel their cars run better on them), they have a cocktail of additives, most of which are there as 'cleaning agents', plus some providing a degree of stabilisation (reducing the speed at which the fuel 'goes off').

For a humble Panda used regularly, 95 octane, E10 fuel should be just fine. Like most other petrol cars on road, that's what it's 'designed' to be run with. If the car is used less frequently than 'normal' (which used to be considered as 10,000 miles a year, although the U.K. average is now nearer 7,500), then there can be a potential benefit from using the 'premium' fuels: the increased octane probably makes no (discernible) difference in everyday driving, but the additives may do. An engine that only makes short journeys or is used less frequently will not get hot enough often enough to keep everything clean – the additives should help here, as well as stopping staleness happening so quickly. And that staleness is the key part.

 

[garyjpaterson]

Genuine question: How stale is too stale? I mean, at what point is fuel staleness going to cause issues - when it no longer is flammable enough to run, or something else prior to that point?

I ask because for carburreted vehicles, it can absolutely be noticed in short periods of time. One of my bikes is very sensitive to the fuel in the bowl going stale, and wont start if its sat for say a week or so with the bowl not being drained (I drain it after every ride and put the contents back into the tank - the larger volume of the tank vs the float bowl seems to stay "fresh" much longer). As such it'll start fine even after months, though I do try and leave it with a near full tank if its going to be sat for any length of time.

But on the other hand I have an old fuel injected BMW that is off the road and was last fuelled up in 2019. The tank is probably only 1/4 full. I think that was before the introduction of the 10% ethanol fuel, but still, 6 years is a long time for fuel to sit. And anytime its needed to, its run just fine. Are there other issues caused by running this old stale fuel despite it clearly being flammable enough to run nicely?

 

[Pugglt Auld Jock]

Genuine question: How stale is too stale? I mean, at what point is fuel staleness going to cause issues - when it no longer is flammable enough to run, or something else prior to that point?

I ask because for carburreted vehicles, it can absolutely be noticed in short periods of time. One of my bikes is very sensitive to the fuel in the bowl going stale, and wont start if its sat for say a week or so with the bowl not being drained (I drain it after every ride and put the contents back into the tank - the larger volume of the tank vs the float bowl seems to stay "fresh" much longer). As such it'll start fine even after months, though I do try and leave it with a near full tank if its going to be sat for any length of time.

But on the other hand I have an old fuel injected BMW that is off the road and was last fuelled up in 2019. The tank is probably only 1/4 full. I think that was before the introduction of the 10% ethanol fuel, but still, 6 years is a long time for fuel to sit. And anytime its needed to, its run just fine. Are there other issues caused by running this old stale fuel despite it clearly being flammable enough to run nicely?

This is a subject which quite interests me, more through my interest in older horticultural machinery than how it affects my cars.

Although, over the years I've messed about with old cars too - like my Imps - Unless bought as "runners" I've always just drained the fuel systems because often I've been going to clean out float chambers etc as part of a comprehensive recommissioning. I then sometimes use the old fuel for cleaning components, especially initial clean down of casings/engine blocks/ etc. You need to be very aware of fire risk of course - I have a selection of fire extinguishers to hand at all times. So it's going to be restarted with fresh fuel.

The horticultural machines are another story. Because these machines are very "seasonal" in use, especially when used domestically, It's not unusual for folk to leave a mower, cultivator, brush cutter/strimmer, hedge cutter or other machine with fuel in the tank and old oil in the engine until they next need to use them, perhaps in the spring. Many don't bother with changing the oil at all, just topping up if lucky. This is not good at all for the engine as contaminants in the old oil then have the opportunity to attack and corrode the working surfaces (like big end journals etc) and solids have a nice long time to settle out and gather in the bottom of the sump and oilways. Bearing in mind that many of these smaller engine have no oil filtration system and rely on the contaminants being suspended in the oil itself Best practice is to change the engine oil after your last cut of the year and run the engine briefly to circulate the new oil round the engine. I mention this because, once the old oil is drained, you can tip the mower up and drain the fuel tank without danger of either spilling oil from the sump or having oil get into the breather system and maybe contaminating the air filter. Of course it's relatively easy to syphon the fuel off if you prefer or perhaps the machine is too big/heavy/awkward to tip up. Personally I advocate an oil change half way through the season too to cut deposition to a minimum.

Sorry, went of on one there a bit didn't I? The relevance though is that, because people know I enjoy messing about with horticultural machinery, I quite often get involved in helping family, friends and neighbors when they find their machine won't start for that first mow - or whatever - of the year. The lawnmowers are usually quite easily started. A clean up and regap of the plug and air filter - Air filters are often a big contributor. Folk just don't clean/renew them - and then, if the machine was used the year before, a small squirt of fresh fuel directly into the air intake and they'll usually start. be aware some engines are especially sensitive to having their air filter in place and are quite reluctant to start without it. Once they fire they'll usually run on fuel left in the tank from the year before but will often lack power and be reluctant to tick over properly. Of greater concern, I find a machine running on "last year's" fuel will run hot if asked to do heavy work - so maybe cutting long grass or cultivating some ground which hasn't been turned over for a long time. My own take on this is that the lighter elements of the fuel mix evaporate which substantially alters the way the fuel burns so I don't recommend running on it. There's also the problem of lacquers building up on metering devices - float valves, jet orifaces and the like. I think it's acceptable, if the tank is maybe only, say, a quarter full of old fuel, to top up with new fuel which should get over the problems and means you don't then have the problem of what to do with the old fuel. By the way, if you have an older machine DON@T RUN IT ON E10. The methanol content will IRREVERSIBLY damage fuel systems in older machines - rubber diaphragms, some alloyed metals, and other parts. The damage is permanent and cannot be reversed by later using low ethanol fuel like premium E5. I run all my old machines on E5 and haven't had any problems. The Americans are very keen on over wintering fuel preservative treatments like this B&S additive: https://www.briggsandstratton.com/eu/en_gb/products/care-products/fuel-fit.html
Might be of use in your 'bike? Here also is some guidance from BP on the subject: https://www.bp.com/content/dam/bp/c...ices/fuels/opal-factsheet-storagehandling.pdf Having read that document from BP "phase separation" looks very interesting and concerning - I'd not heard of this and will now be looking into it some more.

Logically, the fuller you can keep your tank the better because there is less gaseous space then for the lighter elements in the fuel to evaporate into and modern fuel tanks, for many years, do not vent to atmosphere. Our wee Panda only does a couple of thousand miles a year so could be prone to "old fuel" I try to never let her get less than 1/4 tank full and fill to "two clicks" when refueling. It's well worth considering also that modern rotary fuel pumps - that's the pump that takes fuel from the tank and delivers it onwards to the engine - run constantly and recirculate much of the fuel to the tank. These pumps actually use the fuel itself to cool the pump. For this reason I don't like to let fuel levels get much below the 1/4 tank mark. The fact I use Archoil AR 6900-P in every tank, which has a fuel conditioning function, may also contribute in my case.

So, the problem with your question "How stale is stale" is that it's very difficult to give a definitive answer. What engine are you running it in and what fuel delivery system does it use? What was the fuel to start with - ie was it a higher octane premium fuel or "cooking" E10? I find a good "sniff" at the fuel filler gives a pretty good indication - but probably, no, definitely, isn't very good for you!