Sorry, it looks as if you need to use the premium. SOURCE

Engines that are considered high performance require the higher octane of premium. You could economize by filling up with regular when your tank is half full of premium. Over the long haul, a few times not using premium won't hurt but I wouldn't chance using regular exclusively in place of premium.

I have a high performance motorcycle as well as a high performance truck. Both get premium all the time.

Our old MBZ used to get high octane, and then DH switched to regular for a few years. I finally started complaining that the car made a lot of noise. Then he tried an additive, which helped some, but when I learned he was using regular, I suggested he would not need an additive if he used the premium. So he went back to premium and it purred quietly as it ran and idled, whereas we had had a constant rattle using regular.

According to manufacturer, premium unleaded is required.
Fuel Specs

My BMW required premium gas but I used regular most of the time to save the money. The car performed fine and never developed a ping but the catalytic converter developed problems after three or four years. That was an expensive fix so in retrospect it would have been worth spending the extra money on high test gas.

On the flip side, my step-father thought that Premium gas would be better for his car, even though it only required regular. He too had to replace the catalytic converter. Expensive decision in hind-sight.

Thanks for the answers -- and the *reasoning*! I don't know how much longer this car can go on (only 30K miles), but I don't see anything I like better for our needs. It has cost us almost nothing beyond annual servicing and new tires last year. And premium fuel. LOL

The X-Type was a gambit by Jaguar to draw in younger buyers with a less expensive model, then lure them to the larger models. It drew in this buyer, who liked it better than the big sedan she'd gone to the dealer to buy! (It was just as refined *inside* as the big cat, had AWD and was more agile.) A lady loves a bargain!

TV news this morning said eleven years is the average age of a car on the road in the US now. I still see lots of X-Types, and I think they stopped making them in 2008.

" How do you know if your car will take regular gasoline?"

Ask it.

If it's not much of a talker - read the manual: maybe it'll know.

Remember the injunction: "If all else fails - read the book of instructions!".

o j

Consult your owner's manual. It'll state a recommendation for the engine or engines when the car may be equipped with alternate engines.

The grade of fuel needed is related to compression ratio and super/turbo charging. High compression engines need treated fuels to prevent self detonation. A lower compression engine with super charging also needs help for the same reason. At sea level, self ignition begins at compression of 14 to 1, the fuel will self ignite without a spark because at that compression, the compressed air rises above the ignition temperature and the entire charge goes BANG instead of a smooth spreading flame front. As you go up in altitude, the air thins out, there less of it to cram into the cylinder and the self detonation potential decreases.

Typical pinging happens when during the first instant of ignition the cylinder pressure rises and the remainder of the charge explodes all at once instead of a smooth spreading flame front. An engine at sea level needs more anti-knock help than one at 10,000 ft altitude. However, a really active supercharger changes the picture.

The compression ratio may increase if deposits accumulate within the head. Also, deposits can get hot and continue to glow enough to cause ignition.

Catalytic converters oxidizes unburned fuel and tries to complete the combustion of CO (carbon monoxide) to CO2 (Carbon dioxide). Converters fail by overheating or reduced operation. Overheating is caused by too much unburned fuel dumped in to the converter or sitting still for long periods of time with the engine above idle. The usual death of a converter is from contamination of the catalyst rendering it ineffective. Also, the converter can become clogged with deposits. Its passages are small compared to other components of the exhaust system.

Never pour any additive into the gas tank unless it specifically states it is safe for the catalytic converter. Some are not.

A number of converters were killed back when filling stations were switching from leaded gasoline to unleaded. (From before WW2, a lead compound had been used for anti-knock, but lead is one of the things that will coat a catalytic surface and render it useless. Once this happens in an automotive converter, its begins to plug up.) During the change over in fuels, due diligence was not always applied or understood and the fresh fuel was contaminated with the older fuel that remained in the partially emptied tanks. Mix-ups continued either accidentally or by intent until leaded fuel was completely phased out.

I don't think there are any production cars with superchargers. Turbochargers, yes. They do the same thing but mechanically they're very different.

Something I forgot to mention is that today's computerized ignition/emissions control systems are very sophisticated and to a certain extent, can react to pinging by making on the fly adjustments to parameters that are variable and under its control - fuel/air mixture, spark timing, etc. Not so good as to make putting regular into a car that requires premium a good idea.

VW makes a sweet, very powerful high performance, turbo-charged engine that runs on regular.

I agree with you that using retail additives is a bad idea. Buying Top Tier gas (from a busy station so that tanks and pumps are well maintained) is really all one needs to be concerned about to avoid carbon deposit problems.

Looks like we are getting Top Tier when we fill up at Costco. According to their website, their gasoline was formulated to provide five times the US minimum of 'the good stuff' (my technical term for the cleaning agents). Currently, gas there is a few cents higher than at our local filling station, but of course you get three cents BACK, woo-hoo!

BTW, I had 'consulted my owner's manual' before asking here, so I had a pretty good idea we'd continue to use premium gasoline. However, the Wisdom of the KT sometimes provides additional information. Sure enough, I've learned about Top Tier, and that a larger, heavier engine that takes regular fuel can be as productive as a smaller, lighter one that needs premium, and what kills catalytic converters.

SnidelyWhiplash said:

I
don't think there are any production cars with superchargers.
Turbochargers, yes. They do the same thing but mechanically they're very
different.

There were and are passenger autos with superchargers. True, the majority of charged auto engines have turbochargers, but superchargers are the desired choice for high performance. Before the fall of GM, Buick offered a supercharged option. The company I worked for made superchargers for a Ford 4 cylinder model in the 1970s. After Ford mangled the cams and used a small engine to meet increasing EPA regulations, they were left with car having embarrassing performance. Our company hurriedly revived a supercharger design that had been shelved 10 years before. Details were added to the cases for mounting to Ford's engine and a measure of acceptability was regained.

My last Lexus specified premium gas but it seemed to drive perfectly well around town on regular. However when we went to our vacation home in the mountains there were times it hesitated going up the steep road to our place. My mileage was better with premium so I switched back.

It's in the car's manual.