87,89,91 octane

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Status
Not open for further replies.

Ghost10

Full Access Member
Joined
Feb 16, 2017
Posts
620
Reaction score
254
I have a 2018 5.3
No tune, a MIT tube drop in filter, magnaflow clone muffler.

I am a marketing sales manager and drive about 90+ mi a week.

After a 2 months trial of using 87 and 89 octanes.

I get the most MPG and Performance using 89. One other note the exhaust fumes smell better with 89 too. I only use Chevron gas, sometimes I’ll use 76 gas.

Anyone have comments ? I do believe blackbear recommends 89 with my year due to the compression ratios
 

OR VietVet

Multnomah Falls
Supporting Member
Military
Joined
Oct 8, 2014
Posts
19,073
Reaction score
31,180
Location
Willamette Valley
Sounds like the 89 is the way to go, I use the same and have best mpg and performance, but what does the manual say?
 

Joseph Garcia

Supporting Member
Joined
Aug 2, 2018
Posts
6,394
Reaction score
8,323
As @OR VietVet stated, what does the manual say.

I cannot personally help you with this question, as I only run 93 octane, but I have a different motor.
 

Miami-Dade

Staff member
Super Moderator
Supporting Member
Joined
Dec 8, 2016
Posts
3,647
Reaction score
4,280
I have a 2018 5.3
No tune, a MIT tube drop in filter, magnaflow clone muffler.

I am a marketing sales manager and drive about 90+ mi a week.

After a 2 months trial of using 87 and 89 octanes.

I get the most MPG and Performance using 89. One other note the exhaust fumes smell better with 89 too. I only use Chevron gas, sometimes I’ll use 76 gas.

Anyone have comments ? I do believe blackbear recommends 89 with my year due to the compression ratios

@Miami-Dade

What say you Gary?
I now have 135K miles on my 2016 Tahoe LT. Since brand new have been using 87 octane. Mostly Exxon-Mobil and sometimes Sunoco when Exxon-Mobil was nowhere to be found in some areas I was in.

I did put in 89 and 93 while on long highway runs and saw zero difference in mileage and overall performance.

I get 23-25 MPH if it is all highway. Otherwise it is 16-18 for surface streets with traffic. When I am in NYC for weeks at a time I can barely get up to the speed limit with the nasty congestion on the Brookln Queens Expressary and Cross Bronx Expressway so that is always around 16-17 MPG.

To me anything higher then 87 in the 5.3 is a complete waste of money. I think some people are just getting the plausible effect that it runs better using 89 or higher. Just IMHO.

BTW the a/c is constantly on as have never shut it off since day 1.
 

OR VietVet

Multnomah Falls
Supporting Member
Military
Joined
Oct 8, 2014
Posts
19,073
Reaction score
31,180
Location
Willamette Valley
Besides the higher octane, I like the 89 for the additives that help clean the fuel system. At least with Chevron anyway. I have tried 91/93 and saw no gains.
 
OP
OP
Ghost10

Ghost10

Full Access Member
Joined
Feb 16, 2017
Posts
620
Reaction score
254
Besides the higher octane, I like the 89 for the additives that help clean the fuel system. At least with Chevron anyway. I have tried 91/93 and saw no gains.
I did try 91 but felt knocking and hesitant with WOT from 2-3rd so I said NOPE

Where can you find 93, local air port lol!?
I haven’t seen that atleast not at chevron and 76
 

Joseph Garcia

Supporting Member
Joined
Aug 2, 2018
Posts
6,394
Reaction score
8,323
I did try 91 but felt knocking and hesitant with WOT from 2-3rd so I said NOPE

Where can you find 93, local air port lol!?
I haven’t seen that atleast not at chevron and 76
NH has 93 octane, but no E85 that I've ever seen.
 

Fless

Staff member
Super Moderator
Joined
Apr 2, 2017
Posts
10,252
Reaction score
20,309
Location
Elev 5,280
The octane values offered will vary by altitude; here at a mile high (and higher) the octane for regular is 85 and most places don't go higher than 91 for premium. One reason I run E85 whenever available.
 
Status
Not open for further replies.

Forum statistics

Threads
128,795
Posts
1,805,569
Members
91,779
Latest member
wilburMN
Top