Anyone know if it's safe to run seafoam through a 2.5i?

Hello everyone! I have a 2013 Legacy with the 2.5i premium package. I was wondering, is it a good idea to run a can of seafoam through the gas tank of my car? On my old 2002 Dodge Ram when I had it I would occcasionaly throw a can of seafoam through its gas tank and it seemed like it was helping it. Thanks! Edited July 12, 2019 by Alexmed2002

I dont see any reason why it would be a problem, but I dont see the need for it either honestly.

I don't see an issue, but honestly, I've had better results with Chevron Techron Concentrate - the bigger bottle good for up to 20 gallons.

I run that about once a year.

if you use top tier gas, and a good oil (pref. synthetic) there really isn't much need. A decent fuel system cleaner every now and then certainly can't hurt, though.

Works fine ... go a head and use it. . I like the atf treatment better myself...

if you use top tier gas, and a good oil (pref. synthetic) there really isn't much need. A decent fuel system cleaner every now and then certainly can't hurt, though.

 

 

I go to a cumberland farms that's near my house and it's only around a year old (was built from the ground up), so I assume the gas is high quality. From what i've read up Shell and Sunoco are the "premium" gas stations... I also recently got my oil changed at a Subaru dealership while getting a recall taken care of so I would like to think it is a high quality synthtic since that's what I always use.

Edited July 13, 2019 by Alexmed2002

Cumberland farms is not considered a top tier gas station. I personally don't think an additive is needed unless it has carbon build up your trying to get rid of. If you wanted to spend extra money, put 93 octane in your car and it will reduce the timing the ECM is pulling to compensate for the lower octane 87.

Cumberland farms is not considered a top tier gas station. I personally don't think an additive is needed unless it has carbon build up your trying to get rid of. If you wanted to spend extra money, put 93 octane in your car and it will reduce the timing the ECM is pulling to compensate for the lower octane 87.

 

 

Couldn't putting a higher grade gas in an 87 octane only vehicle cause issues though? Like making the engine retard its timing and such? When I had my truck and I had a tuner that was a common problem people had if they didn't do their research...

no - unless you have an issue such as carbon buildup resulting in knock at the lower octane, there will be no benefit of or detriment to using the higher octane fuel. (other than a lighter wallet!) - the engine will only be pulling timing if there is an issue with the combustion, and a fuel that is more resistant to premature detonation isn't going to do anything otherwise. The 91+ octane is needed in turbocharged or other high compression engines, but doesn't really benefit much else.

 

 

On our van, I always put in the mid grade as folks in the petrochem industry have suggested to me that the additive package is better controlled in the upper grades. (no actual data, though)

no - unless you have an issue such as carbon buildup resulting in knock at the lower octane, there will be no benefit of or detriment to using the higher octane fuel. (other than a lighter wallet!) - the engine will only be pulling timing if there is an issue with the combustion, and a fuel that is more resistant to premature detonation isn't going to do anything otherwise.

 

You're making an assumption that 2.5i doesn't detonate with 87 octane. I data logged my '12 2.5i with about 4k miles and the DAM was around 0.4 with 87 octane. 93 octane gave me a 1.0 DAM. My 2009 2.5i Outback is the same way. Maybe its improved on the FB25 that Subaru put in 2013. I am not the only one, very few 2.5i Subaru owner catalog their vehicles.

 

That being said on my Outback, I usually run 87 octane anyways and just put in 93 when I pan on towing.

That's surprising! I wouldn't think it would knock with the required octane! (you can buy 86 at some stations here, but we're at elevation) I always wonder what the allowable uncertainty is on pump gas - is 91 actually 91 +/- something? They don't sell 93 here at most stations. 91 is "premium" - down in Carlsbad, I remember not even being able to find that! 90 was premium!

You're making an assumption that 2.5i doesn't detonate with 87 octane. I data logged my '12 2.5i with about 4k miles and the DAM was around 0.4 with 87 octane. 93 octane gave me a 1.0 DAM. My 2009 2.5i Outback is the same way. Maybe its improved on the FB25 that Subaru put in 2013. I am not the only one, very few 2.5i Subaru owner catalog their vehicles.

 

That being said on my Outback, I usually run 87 octane anyways and just put in 93 when I pan on towing.

 

Correct me if I am wrong, but 1.0 DAM is what you're supposed to get right? And 0.4 DAM is low?

DAM varies from 0-1 on most newer Subarus (it was between 1 and 16 on 05 and earlier) - 0.4 is low, 1.0 is perfect. there's a threshold below which your ECU puts the car in limp mode.

DAM varies from 0-1 on most newer Subarus (it was between 1 and 16 on 05 and earlier) - 0.4 is low, 1.0 is perfect. there's a threshold below which your ECU puts the car in limp mode.

 

Oh I see. Makes sense.

Couldn't putting a higher grade gas in an 87 octane only vehicle cause issues though? Like making the engine retard its timing and such? When I had my truck and I had a tuner that was a common problem people had if they didn't do their research...

 

Is the car 87 octane only? I read in my owners manual that you should use 87 octane fuel or higher. I'm a bit confused on what that means, but I've been using 93 octane recently and notice no difference, only a little better fuel economy than I got with regular.

Is the car 87 octane only? I read in my owners manual that you should use 87 octane fuel or higher. I'm a bit confused on what that means, but I've been using 93 octane recently and notice no difference, only a little better fuel economy than I got with regular.

 

My car says 87 Octane only on the inside of the gas cap. It's the 2.5 engine too.

My guess is that's meant to suggest that you shouldn't use a higher-ethanol blend (E15 or E85), not that you can't use higher-octane E0-E10 fuels. Like DrD123 alluded to, octane rating is a measure of resistance to detonation (fuel/air mix igniting due to something other than the spark plug firing), and as long as it's good quality fuel, running a higher octane rating shouldn't be a problem.

My guess is that's meant to suggest that you shouldn't use a higher-ethanol blend (E15 or E85), not that you can't use higher-octane E0-E10 fuels. Like DrD123 alluded to, octane rating is a measure of resistance to detonation (fuel/air mix igniting due to something other than the spark plug firing), and as long as it's good quality fuel, running a higher octane rating shouldn't be a problem.

 

Ya now that I think about it, I somewhat want to try running a tank full of 91/93 Octane once it's time to refill. I'm curious to say the least, but at the same time I don't know if I want to risk it... from what i've read up most people said they didn't see an improvment with anything over 87 octane and some people even said they had pinging or knocking too.

No scientific data here and could just be placebo, but I have a '13 2.5i and was noticing some slight knocking on start up and a some lag when getting on it (car is at 170k miles, mind you). Dumped some 91 in there for 2 fill ups (noticed slightly lower mpg actually), and then used high mileage fuel additive the following 2 fill ups of 87. Car seems to be running a bit more smoothly now and my mpg has gone back up to about 25, where as it was dipping to 23/24. Still plan to do some maintenance to address potential carbon build up and/or other high mileage wear.

No scientific data here and could just be placebo, but I have a '13 2.5i and was noticing some slight knocking on start up and a some lag when getting on it (car is at 170k miles, mind you). Dumped some 91 in there for 2 fill ups (noticed slightly lower mpg actually), and then used high mileage fuel additive the following 2 fill ups of 87. Car seems to be running a bit more smoothly now and my mpg has gone back up to about 25, where as it was dipping to 23/24. Still plan to do some maintenance to address potential carbon build up and/or other high mileage wear.

 

My legacy has just under 84k, my mother drove it up until 82k and she never did add anything like Chevron Techron or anything lmao . I might add some soon just for the heck of it.

Modern engines are calibrated to be right on the edge of knock - that's where the most efficient point is. Pulling around two degrees of timing when the engine is making good power (on its recommended fuel) is pretty standard from a production calibration perspective.

 

That being said, you can get a very small bit of power back from that two degrees, say by putting 93 octane in a car intended to run 87, as its almost guaranteed to have no knock.

 

Personally, I've found its very important where you get your gas from. Stations like those at walmart and grocery stores usually get fuels as cheap as they can, meaning their quality control and additives are lacking. Out of the two times I've gotten gas from a walmart, both times I could physically feel the engine running rougher by the time I got out of the parking lot than when I had pulled in.

 

Now, I try to only get Top Tier gas. Top Tier is a sort of "members club" of gas stations whose fuels meet a higher standard of quality. Obviously this is based on my own experiences, but its my way of preventing excessive carbon build up.

Modern engines are calibrated to be right on the edge of knock - that's where the most efficient point is. Pulling around two degrees of timing when the engine is making good power (on its recommended fuel) is pretty standard from a production calibration perspective.

 

That being said, you can get a very small bit of power back from that two degrees, say by putting 93 octane in a car intended to run 87, as its almost guaranteed to have no knock.

 

Personally, I've found its very important where you get your gas from. Stations like those at walmart and grocery stores usually get fuels as cheap as they can, meaning their quality control and additives are lacking. Out of the two times I've gotten gas from a walmart, both times I could physically feel the engine running rougher by the time I got out of the parking lot than when I had pulled in.

 

Now, I try to only get Top Tier gas. Top Tier is a sort of "members club" of gas stations whose fuels meet a higher standard of quality. Obviously this is based on my own experiences, but its my way of preventing excessive carbon build up.

 

What gas stations do you go to? The only "top tier" gas station near me is sunoco...

Depends pretty heavily on where you drive. In Upstate New York, there's an occasional Valero, some Mobil's, and the standard sunoco's. In the Pittsburgh area, its limited to Exxon and BP mainly. When I lived in Texas, Valero and Shell were the most common.

 

Sometimes they can be out of the way, so plan it into getting groceries or visiting friends that might be near one.

 

In New York, I've found Speedway to be reliably good even though they aren't registered as Top Tier. Not sure if they're around Mass...

Depends pretty heavily on where you drive. In Upstate New York, there's an occasional Valero, some Mobil's, and the standard sunoco's. In the Pittsburgh area, its limited to Exxon and BP mainly. When I lived in Texas, Valero and Shell were the most common.

 

Sometimes they can be out of the way, so plan it into getting groceries or visiting friends that might be near one.

 

In New York, I've found Speedway to be reliably good even though they aren't registered as Top Tier. Not sure if they're around Mass...

 

Ya Speedway bought out a lot of different Hess gas stations as well as others. They've gotten more and more popular.

Seems like a ton of stations were taken over by Speedway around here - Conoco, shell, etc. - lots of different ones. Definitely not registered as top tier...