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Discussion Starter #1
I'm just curious if it is allowed (and the car can compensate for it) or if it will lead to excessive wear over time. Depending on the price in my area sometimes it makes sense to fill up with 87. I have read online that most newer turbo cars can handle it just fine, but older ones cannot without causing problems over time.
 

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Yes- it's in the owner's manual.
OK to use 87 octane. Improved performance and mileage with 91 Octane.
 

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Shouldn’t be an issue according to the manual, personally I run 91 Octane in mine :)
 

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I run 91 in mine too. I'm just trying to avoid problems down the road with the "High Pressure Direct Injection" system that our 2.0T is equipped with. A common problem with almost all, the most famous being the Ford EcoBoost turbos is carbon fouling and build up in the combustion chamber around the injector port. Very expensive fix!!! I'm not taking any chances. I run nothing but Chevron Premium with Techclorine, or Shell Premium.
 

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As noted in the answers above, 87 octane is permitted, while 91 or better is recommended for maximum performance. In cases where you are doing a lot of fully-loaded towing or running hard in very hot weather, you might consider a premium grade of fuel. For light-duty use -- and that's the kind of use most cars get, even most Cherokees -- 87 octane works fine and results in a significant cost-savings.

An important point to add is that, whether you're inclined to run regular or premium, you'll be doing your engine a favor if you use gas that is Top Tier(tm) certified. Top Tier gas denotes a fuel performance standard, and typically includes the use of an enhanced, engine-cleaning detergent package.This standard goes well beyond the minimum federal requirements that all gasoline should meet. Look for Top Tier labeling on the pump. Gas stations that offer this specification are required to include it with all grades of fuel.

The bottom line is that, if you run 87 octane in your 2.0L Turbo engine, Top Tier gas gives you a well-proven engine-cleaning advantage that helps to safeguard against carbon build-up and other engine deposits.

More info: Homepage
AAA: Not All Gasoline Created Equal | AAA NewsRoom
 

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The problem with the extra detergents in TopTier fuel is...none of it touches the back of the valves where it is needed to prevent carbon buildup. The 2.0 is a direct injection engine, all the fuel bypasses the intake ports, so the detergents can’t do what they are designed to do.

I’m not saying to avoid TopTier fuels since detergents aren’t their only difference, but they don’t provide all the advantages seen with TB or port injection.


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The problem with the extra detergents in TopTier fuel is...none of it touches the back of the valves where it is needed to prevent carbon buildup. The 2.0 is a direct injection engine, all the fuel bypasses the intake ports, so the detergents can’t do what they are designed to do.
The suggestion that direct injection engines cannot benefit from the detergent additive package in Top Tier fuels is not consistent with the results obtained in the testing performed for AAA. It is also inconsistent with results I observed while working with a major European manufacturer well-known for its leadership in DI engines. Based on this experience, Top Tier fuel does, in fact, have a beneficial effect in the reduction of intake valve deposits (as well as fuel injector deposits and combustion chamber deposits) on direct injection engines. The full AAA report is available here:


A couple of specific references to the engine cleaning and performance/emissions enhancing properties of Top Tie fuel in direct injection engines can be found in Section 2 of the report on pages 9 and 10; and the sub-section on emissions found in Section 5.3 – page 19.

As a friendly aside, I don't have a dog in the fuel fight, don't own a gas station or oil company, don't make my living in the fuel business and have no affiliation with any fuel company or AAA. However, I have no reason to disbelieve the study commissioned by AAA. I also find no reason to doubt that manufacturers like FCA (and more than a dozen others) have made a proper engineering analysis of the Top Tier program before they recommended use of these fuels.
 

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I’m not going to argue the point, I use Top Tier fuel so there is no impact to me, and I don’t recommend not using TT fuel In a Jeep. However, the fact that DI engines (most at least) result in increased intake valve deposits is of at least some academic interest to me and I encourage discussion.

I note that the AAA test referenced used a Ford 2.3 port injected engine, not a DI engine. Therefore, the test results neither confirm nor deny any advantage to the use of Top Tier fuel in preventing intake valve deposits in DI engines. Careful reading of the other references in the report shows they do not specifically state that TT fuels reduce intake valve deposits on DI engines, however they do mention injector tips.

Detergents have other advantages, including as above keeping injectors clean and reducing some buildup in the combustion chamber, so higher concentrations of the correct types of detergents can be helpful. Some engine designers have even configured their DI systems to deflect some fuel onto the intake valve stem, acknowledging the problem. A few other discussions follow:





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Just to cause a riot read below.

I think that anyone that uses fuel higher than recommended by your vehicles manufacturer is just throwing $$$ away or love to support the major oil companies! You may not buy any Jeep for a fuel economy vehicle but it's pretty dumb throwing your money away. Jeeps lean toward crappy MPG anyway! Around here there is at least 20 cents difference tween 87 and 91 octane! If your doing normal driving and not feeling or hearing any problems with 87 and it runs good and it's recommended, save your $$$ for goodies, lotsa Jeep goodies out there!

Go jeep!!!
 

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Just to cause a riot read below.

I think that anyone that uses fuel higher than recommended by your vehicles manufacturer is just throwing $$$ away or love to support the major oil companies! You may not buy any Jeep for a fuel economy vehicle but it's pretty dumb throwing your money away. Jeeps lean toward crappy MPG anyway! Around here there is at least 20 cents difference tween 87 and 91 octane! If your doing normal driving and not feeling or hearing any problems with 87 and it runs good and it's recommended, save your $$$ for goodies, lotsa Jeep goodies out there!

Go jeep!!!
If you want your vehicle to be pulling timing all the time due to knocking, then by all means save your money and run 87 octane. It's not like its publicized everywhere that the Turbo requires 91 octane for top performance. Want to cheap out on gas, don't go with the turbo.
 

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I’ve pulled about 4000 lbs with 87 octane without issue. drove about 100 miles of flat’ish land That way. Wasn’t by choice as we were in a rural area. Won’t get best performance, but if your not towing etc, not going to make a huge difference. Unscientifically, I’d guess 10-20 HP loss. I mix and match 89/91 octane periodically if there’s 20-30 cents difference.
 

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How do you know there was no issues? Were you data logging to see that there was "no issues"
Car & Driver tested an Ecoboost 3.5 F150 and saw a dyno tested 20hp at the wheels loss in HP vs the 93 octane ford recommended when they used 87 octane. They also lost 0.5s in the 1/4 mile and the trap speed dropped 4mph.
So really running 87 octane is going to drop the performance of the engines, so even if it goes down by 10-15hp, now you have less HP than the V6, yes you started out with more torqure but generally if you are losing HP you are losing torque so now you've got a cherokee with less HP than the V6 and possibly a bit more torque. Seems like a stupid idea to hamstring the performance of an engine just to save a few bucks at the pump.
I'd suggest doing logging of Spark advance and knock on a tank of 87 octane and then a tank of 91 octane and see the differences.

Differences can be found. It was very easy for me to tell when I got a tank of bad gas when running my Tuned 2016 Trailhawk. Tuned for 94 octane. Filled up at a different station that advertised 94 octane. After about 10 minutes timing was being pulled and tons of knock was being logged.

Again, I like data I dont have a turbo so someone with a turbo do some logging and prove me wrong.
 

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Yeah I was data logging.
 

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Discussion Starter #15
I've been putting 87 in my turbo for the past two months and although the mpg is worse, the spread between 87 (regular) and 93 (premium) in my area is 60+ cents USD per gallon. So in my opinion as long as the spread is > 30 cents I'm going to continue to put regular in. Once it is close to 30 I will mix to get around 90 octane.
 

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If you did data logging how can you be so sure it's not pulling timing, did you do extensive logging with 87 octane and note the timing advance and boost, and then do the same with 91 octane. Since you don't have access to the PCM timing tables (unless you have HP Tuners) I think it would be hard for you to show it's running just fine.





Note the timing advance in the first picture, 30 degrees and the air charge (because its a speed density system) 650.2mg

Refer to the table for timing almost 7000rpm and 30 degrees timing, so I know my engine isn't pulling timing and is maxing out the timing tables and isn't knocking.

I'm sure you have data like that to support your theory.
 

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I have run 87 or 88 for most of 28000 miles .. runs fine.

If I'm towing esp. in the summer I will fill up with 93.
its nearly 50% more for 93 than 88 currently.

If you put it in sport mode with 87 it feels better than 93 in auto.. unless you are flooring it all the time who cares?

For me the definitive answer is the owners manual
Requires 87, recommends 91
 

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RXCFGLUBC5A2HZDX35KFG3KZ5Q.jpg Run what ya brung!!! That's probably regular 87 in the "Police Interceptor". The government is cheap that way!!! They have much more creative ways to waste money...
 

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your engine, like any is based on compression. Octane compresses at different rates and has different flash-points. if your engine is designed for 87, run 87. if 93, yup run 93. If you have done mods (typically a lot of them not just intake and exhaust) then you may be able to run 93.
this video explains it nicely.
its not magic, its science. Running 93 in an engine designed for 87 would (over time) be very bad. running 87 in an engine designed for 93 would have similar results.
 

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Wow, this thread suddenly went south fast. What does a Ford Crown Vic have to do with the OP’s question? And octane is a measurement not a thing, it cant “compress”; does nothing to answer the OP’s question....




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