Fuel and Oil Additives

[Dino]

In general, as Subaru engines are powerful, do fuel additives and oil additives provide any benefit? I was thinking of trying an injector cleaner as these tended to work well on my former cars because the kerosene in these cleans and adds a bit of torque too once run through in the fuel.

 

Does anyone here use injector cleaner or the like on a flat four engine?

[Gambit]

Fuel is fine you shouldn't ever need to add anything to the oil with the right service as it will be done with fresh oil before t should get any real nasties in there. I've used a few fuel injector cleaners from time to time. But it's also said shouldn't always need to if you use the top Ron stuff but I see no harm in it :D 

[Dino]

Thanks Gambit. Yes its interesting... I wondered whether injector cleaner may cause problems in a 200+ BHP flat four, like the plugs may break up or something. The oil additives are interesting though because they seem to do a good job at sealing worn pistons in the barrel and allowing them to glide better, similar to the additives now being added to Ron 98 petrol and synthetic oil.However, my experience and testing of these shows me that some are very good at doing the job, however don't use PTFE additives - they are BAD news.

[Gambit]

No problem mate. I wouldn't take it as gospel I'm only going from what I have read and seen from other people and recommendations :) But I was told the oil stuff that helps the pistons seal themselves and glide better, is what does the problems with the engine being built the way it is. But as I said before the oil with these should be changed long before anything nasty happens really I know it's the age of the oil that does most damage due to the friction. and because of what I have read never used it myself and won't just to be safe than sorry :)

I've used and know people who have used injector cleaner in 9 years I've never seen a problem with mine or heard of any coming from using it from other owners  :)   

[Dino]

Nice one. Do you know how much petrol the Hawkeye Impreza WRX / STI tank holds? I've read the owner's manual from end to end and it does not say, rather it only advises on there being 2 galls left when the low fuel light comes on.

[Scooby Pete]

50ltrs 10 Gallons with 10 ltrs 2 gallons of reserve I think.

[Gambit]

I think it's a 50 Ltr tank I believe. But I'm going on from when my tank's been nearly empty I filled it and got about 49Ltrs in it. should get about 50 miles from the fuel light so I was told but been told these don't give any warning if they cut out from no fuel like other cars they just stop :D But never been that low to find out :)

[bowthruster]

Dino hi and welcome.Talking of additives etc,what are you thoughts on engine flush?what you add to the oil run it for a while then drain out ready for new oil.Some say good stuff some say bad?

[Gambit]

Again as before its really shouldn't be needed, and have heard more bad reports after people have used it. I've not used it and wouldn't advise anyone to myself.

[Dino]

Hi, thanks for the welcome bowthruster. Engine flush is thought to be bad news these days. In theory, there shouldn't be any carbonised black deposit build up in a modern engine using Synthetic Oil due to the additives in it already. Only the Oil Filter will tend to collect any deposits in modern engines. The thicker oil residue will settle at the bottom of the sump and drain out on oil change at the recommended regular manufacturer intervals. Volvo for example do not recommend using ANY engine flush on service these days as they say it does more harm than good because it loosens up the engine parts de-carbonising ports, valves, valve seats and push rods etc and then things wear out quicker or go BANG! What I have heard is to drain the old oil out, but then get some really cheap "thin" synthetic oil like Comma 0W/20 or 0W/30 and use that to flush the engine, but leaving it in for two hours first to do its stuff, turning the engine over occasionally. Then drain this dirty oil out again to top up with the manufacturers specification oil (5W/30 mobil or the like).

[bowthruster]

Cheers for that gambit.Dino thanks for that reply.I bought some when I first got the car in feb,but I daren't  use it :o. its just sitting on the shelf.So in the bin tomorrow.I heard about using the cheap oil as a flush,but do you use the original filter then replace when you use the good oil.

[Dino]

Good point... You can flush with cheap thin oil with the old filter still in. In theory, any deposits from the top of the engine will settle out in the old oil filter which you can then remove. Put the new oil filter in and then put in the new 5W/30 oil.

[bowthruster]

Cheers dino.Ive got a classic my99,ive used 10/40 in the past so that opens another can of worms..

[Dino]

Check out these links to get the oil spec for your car. Bear in mind, if you have a very high mileage Subaru, then using a thicker oil such as 10W/40 over 5W/30 is ok because it may need it to improve compression and help reduce wear.

Mobil: http://ew5.earlweb.com/search.php?site=105®ion=120&language=5&brand=106

Castrol: http://oilselector.castrol.com/c/uk/eng/search

[bowthruster]

mobil says 0/40w and castrol say 0/30

[Dino]

ok so using a grade higher such as a 5W/xx should not be a problem, but using too thick an oil could cause a head gasket to blow if you push your engine too hard - worst case. The /30 and /40 are not a lot of difference, the /40 is usually used for higher temperatures such as the med countries. The mobil one will say /40 for this reason as it expects you to be in the USA near its Exxon plant probably where its much warmer lol. And if its showing Edge Oil for castrol then that's cos their new oil tech means it can be thinner but cause less wear. I stick to 5W/30 though for UK spec due to the lower winter temperatures but also because of the diverse range of temperatures summer to winter. Using the right oil when you change it will make all the difference to how it runs, pulls and drives.

[Gambit]

Have to take into account any mods though I know modded cars should run 10w 50 I've been running my bugeye on that since the rebuild but the blobeye that is pretty much standard I think is 5W30 off the top of my head :)  

 

But I have friends that will up it depending on age of the engine to help stop it smoking as much.

[Steveuk260.Esq]

I think it's a 50 Ltr tank I believe. But I'm going on from when my tank's been nearly empty I filled it and got about 49Ltrs in it. should get about 50 miles from the fuel light so I was told but been told these don't give any warning if they cut out from no fuel like other cars they just stop :D But never been that low to find out :)

50 miles reserve? You are getting petrol cars confused with diesels. Diesels =50. Petrol =30. +- depending on driver.

[Dino]

30 miles petrol on reserve means about 5 litres or 1 gallon (4.54 litres) which is about 30 miles of fuel. But then it depends on how you drive it ;) I noticed though that sitting in traffic uses hardly any petrol at all, so that's a relief.

 

I put some fuel injector cleaner in with a full tank of petrol to clean the system - what the hell, I want to get my engine feeling good because it has what I can only describe as a slight "burble" or miss when running idle <_<. Or, is this is a characteristic of the Subaru flat-four boxer engine? Anyone advise me here?

[Jay762]

they do idle lumpy

[Steveuk260.Esq]

I second that.