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brucepick · 03-16-2012, 10:45 PM

'97 Honda Civic HX, 250K miles, head rebuild a year ago, stock engine, many aero and electrical mods.

I've been using Marvel Mystery Oil (MMO) in the Civic since January 17,2012. For this car, it's a winner.

The Civic HX offers lean burn and one of my gauges lets me know when I've achieved it. LB seems to net me about a 10% mpg increase, maybe 15%. Lean burn state was nearly always limited to 61 mph and above when in 5th gear, though drivers of other HX's told me they had lean burn below 50 mph. What hypermiler wants to spend all their time above 61 mph to save fuel?? But I could only get low speed lean burn for a couple miles or so at the start of a highway trip, and that was all.

Anyway, at one oil change I added 1/2 the suggested concentration of MMO to the crankcase (suggested = 20% of sump capacity) and 1/2 the recommended concentration to the tank (suggested = 4 oz/10 gal). Ta-daaahh! Lean burn was there, down to about 46 mph. Since then, I've upped the concentration of fuel tank MMO to the recommended amount, 4 oz/10 gal. Nice markings on the 1 qt bottle help you get it right.

The MMO in the tank is definitely needed. The first time I filled up and did NOT add MMO to the tank, low speed lean burn went away. Pulled off road, added a few ounces, and lean burn came back. Thankfully circulating fuel pump systems help mix up whatever you may have in your tank.

I don't know whether the MMO in the oil sump is helping this engine any, but I'm continuing with MMO there at 10%.

True that MMO costs something like $20/gallon, bought in quart sizes. However per fillup it's only about $0.60 or so, not even worth thinking about, IMHO.

03-16-2012, 10:45 PM	#1 (permalink)
brucepick OCD Master EcoModder Join Date: Dec 2007 Location: Eastern CT, USA Posts: 1,936 Outasight - '00 Honda Insight Team Honda Gen-1 Insights 90 day: 54.18 mpg (US) Thanks: 431 Thanked 396 Times in 264 Posts	Success with Marvel Mystery Oil '97 Honda Civic HX, 250K miles, head rebuild a year ago, stock engine, many aero and electrical mods. I've been using Marvel Mystery Oil (MMO) in the Civic since January 17,2012. For this car, it's a winner. The Civic HX offers lean burn and one of my gauges lets me know when I've achieved it. LB seems to net me about a 10% mpg increase, maybe 15%. Lean burn state was nearly always limited to 61 mph and above when in 5th gear, though drivers of other HX's told me they had lean burn below 50 mph. What hypermiler wants to spend all their time above 61 mph to save fuel?? But I could only get low speed lean burn for a couple miles or so at the start of a highway trip, and that was all. Anyway, at one oil change I added 1/2 the suggested concentration of MMO to the crankcase (suggested = 20% of sump capacity) and 1/2 the recommended concentration to the tank (suggested = 4 oz/10 gal). Ta-daaahh! Lean burn was there, down to about 46 mph. Since then, I've upped the concentration of fuel tank MMO to the recommended amount, 4 oz/10 gal. Nice markings on the 1 qt bottle help you get it right. The MMO in the tank is definitely needed. The first time I filled up and did NOT add MMO to the tank, low speed lean burn went away. Pulled off road, added a few ounces, and lean burn came back. Thankfully circulating fuel pump systems help mix up whatever you may have in your tank. I don't know whether the MMO in the oil sump is helping this engine any, but I'm continuing with MMO there at 10%. True that MMO costs something like $20/gallon, bought in quart sizes. However per fillup it's only about $0.60 or so, not even worth thinking about, IMHO. __________________ Coast long and prosper. Driving '00 Honda Insight, acquired Feb 2016.