1995 Volvo 850 GLT, Spark Plugs?

Viraaj · Post by **Viraaj** » 21 Feb 2007, 17:17

Sup people have a question. What the best type of spark plug to use. And at what millage should the spark plugs be chaged at, the volvo has 75,000 miles and the plugs have never been changed.

greasefingerss · Post by **greasefingerss** » 21 Feb 2007, 18:09

The Bosch copper FR 6 DC is what my Owners manual states.

They should be replaced every 30,000 miles. Have fun taking them out since they have been in there that long.

Post by **kelvin6** » 22 Feb 2007, 11:48

Well, the dealer does sell a set of plugs (also can purchase from FCP groton) for the NA, which is what the engine of your 1995 850 GLT is, for $12~13. I'm currently using the bosch platinum +4 and honestly i don't think there is a any performance or any fuel economy difference from it compared to some regular plugs. Next time, i'm going with the Volvo plugs, its cheaper too.

I may seem like a nut, but I do change them out almost every year, even though I only drive about 7000 miles a year all city driving, because I do treat the engine pretty harsh... There is no way i would change everytime with the Bosch Platinums +4 due to high cost and little to no difference to the factor Volvo plugs. So thats why next time i'm just going to pick up the factory plugs, because they work and they are cheap.

Viraaj · Post by **Viraaj** » 22 Feb 2007, 15:58

lol, cant decide between Bosch or NGK. Duno which one is more relible and also gives more performance

Viraaj · Post by **Viraaj** » 22 Feb 2007, 16:04

I talked to many volvo owners, most of then told me that Bosch does not work well, alot of problems but duno if thats true??

Post by **MadeInJapan** » 22 Feb 2007, 16:27

Viraaj...don't go NGK on a Volvo.
Go with the basic copper Bosch plugs or like someone else mentioned, Volvo plugs...you can't go wrong at all with the later- tested and true. Just make sure you gap them right....at .028inches.

zenmervolt · Post by **zenmervolt** » 22 Feb 2007, 17:19

MadeInJapan wrote:Viraaj...don't go NGK on a Volvo.

Curious why not. Especially on turbos.

I realise that different cars react differently, but my experience has been that NGK copper plugs work best in the cars I've had in the past. Partially because they tend to run slightly colder than Bosch plugs for a given heat range spec. They've been the preferred plug for most 951 owners for quite a while.

Just curious what issues have been seen in Volvos when using NGK plugs.

Post by **MadeInJapan** » 22 Feb 2007, 20:05

It was something I had read so I went back and searched. I personally used to use NGK on all of our Honda's. Anyway, what I found was that NGK BKR7E plugs are fine. However, many have had problems with the Iridium plugs. I guess I spoke to soon and I should have said to avoid iridium on the NA Volvo engines. I have read that Champion coppers are also decent. In fact, I believe these are listed in the owner's manual as an alternative.

greasefingerss · Post by **greasefingerss** » 22 Feb 2007, 20:18

The heat index is the only important factor for spark plugs. If the heat range is correct then it does not matter whose plugs you select. The engineers spent countless hours determining things like this. This is why one should never deviate from the original heat range specified by the manufacturer.

If the heat range is too high then the engine may ping as it will retain more heat. If too low then incomplete combustion may occur.

One could choose a colder spark plug but other tuning applications would need to be employed as well.

zenmervolt · Post by **zenmervolt** » 22 Feb 2007, 21:03

Definitely agree about avoiding the iridium plugs. I'd even go so far as to say to avoid platinums in turbocharged engines, there have been some cases of platinums disintegrating in 951s.

Besides, Iridium plugs are $12/plug. Copper plugs are $2/plug. Coppers last 30K, Iridiums last 100K. That makes coppers something like 45% less expensive in the long run.