PlotPoint

All -- Headed out today for a freeway run and then a pre-test for Smog. Barely passed two years ago (high NOX). The results will not be sent to the California DMV. This is '94 LS400.

AutoZone had a sale on the smaller bottles of Chevron Techron fuel system cleaner, so, in preparation for the smog test, I did one treatment about six weeks ago, then had the oil changed. Their instructions said a second treatment "might" give added benefits, so I decided to go ahead and use the second bottle. The tank was "near empty" (as they instructed, and I filled up with what I thought was 12 gallons (as they instructed). I started the car and ran it for less than two minutes before I realized the receipt I was reading was showing $12, not 12 gallons. I quick shut the engine off,then added more fuel to reach 12 gallons (taking into account the small amount of fuel I had already added). In other words, for a very short period, the Techron circulated mixed with only 3 to 4 gallons, not the required 12 gallons of fuel. I imagine the system got a good cleaning!!

Question. Should I get yet another oil change before the pretest? If that second treatment pulled off more deposits, etc. will that impace NOX readings. I actually forgot that an oil change is recommended after a Techron treatment., but just don't know whether the fact that it is a SECOND treatment (within two months timeframe) would mean that that is not necessary.

Thanks in advance for any recommendations.

sha4000

iTrader: (1)

I never did an oil change when using Techron or seafoam in the tank.

PlotPoint

Thanks. There is every answer from an absolute yes to an absolute no on whether one should change the oil after use of Techron. Next time I use that stuff, I will use it just once, and get one oil change after. I am not going to bother with another oil change this time.

python

iTrader: (4)

what r we talkin about here..in the gas tank? then changing ur oil? if so thats a load of crap.

RA40

iTrader: (6)

The fuel system cleaner is not going to really impact the high NOX readings. That is EGR. Clear the EGR valve and the associated pipes, the NOX will be barely readable.

timmy0tool

iTrader: (7)

yep i suspect you have leaking EGR pipe, which is very common. fix that pipe, and you should be able to pass smog. fuel/oil treatments i log into the mysterious file, as it's hard to prove if they actually work or not.