i agree with jo. when i first bought my 850 turbo wagon i headed to the rockies for 3 weeks. i blasted up and down those hills testing various grades and noticed no difference. up here in canada there is about a $6 difference per tank. we get ripped up here on supreme. oh but they give you ten cents extra in coupons. RIP 95 850 turbo wagon 697000km.

If you do the math, $$ per mile, 93 octane is cheeper than regular. You will run sufficiently futher on each gallon to justify the higher cost. Try it and see for yourself.

I have had poor luck with regular gas.

I keep track of every gallon of gas I buy, and usually check mileage on a trip, or once or twice a year, calculating 4 or 5 tankfulls.

I don't know about 850s, but I have read that the first thing a 740 system does when pinging is detected is add fuel to the mixture as it works faster than retarding the timing and cools the combustion chambers.

I think that this can account for poor mileage using regular gas.
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'96 855R,'64 PV544, '67 P1800, '95 855, '95 854, the first three are mine, heh, heh, 405,000 miles put on 8 bricks

My owner's manual says to use a minimum 91 octane so I'd listen to the Volvo engineers and use at least 91 octane since they designed the car and maybe they know something.

I always try to also avoid ethanol since by caloric content it contains fewer calories per gallon than straight gasoline.

My Volvo comes from the-land-of-$7-gasoline, so I don't worry about saving a few cents per gallon. Gas is still a lot cheaper here than that fizzy French bottled water. If saving a buck or two every fill up is worth the trouble to you than by all means do it. If you do it for a year you'll probably save enough to buy one or two shares of Exxon-Mobil!

-BTC

'98 V70 T5 5-speed, 168k mi, velour cloth seats, front IPD stabilizer bar, rear factory HD bar, Bilstein HD, Volvo strut tower brace and skidplate, e-codes, XC grill, Lidatek LE30, V-1, Mobil-1 since new

"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." -- Douglas Noel Adams (1952-2001)

The knock sensors will retard the timing to eliminate pinging, valve rattle. There will be a loss of horsepower, but at steady spead on the highway you are not using much horsepower. Some will claim a fuel mileage difference as well. I am not an expert, so I like to follow the manufacturer's recommendations.

You only need 93 octane if you are going for maximum boost, a lot! Mid grade works very well. Regular can be used in the midwest highways, flat and steady cruising speed. Some readers claim the milage will drop with lower grade gas because the timing is being retarded, and if that is your case, inccrease the octane.
The knock sensors will keep the engine from knocking even with 85 octane.

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)

I have a low presssure turbo V70. I feel no difference in performance between mid grade 89 octane and premium 93 octane.

Theres a slight dcrease in performance with regular gas. I am using regular branded gas now, with midgrade every fourth fillup.

Save your money and drop to midgrade, you won't notice any difference
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'88 240, '92 745, '98 v70 -John, Tampa Bay