AC Delco 41-110 in 2000 Tahoe 5.3L

[SmokeEater]

I switched out the stock plugs during a tune up in June 2012 with AC Delco 41-110 Iridium plugs per the AC Delco book and Rock Auto lookup. Since the tune up, I've always felt the gas mileage has come down. I'm getting 14-15 MPG on the highway keeping it under 70 MPH, when I used to get around 17 MPG. I chalked it up to ethanol fuels.

I just read that AC Delco is no longer recommending this plug for 2000 - 2005 5.3L vortex engines. They are now recommending 41-962 Platinum plugs.

Does anyone have details on why they made the switch? I'm curious to know if the 41-962's are more efficient for this engine and if I should make the switch to the latest recommendation. The $50 cost will quickly be returned if I get 3 MPG back.

Is anyone else running the Delco 41-110 plugs in a 2000 to 2005 5.3L and noticing a drop in fuel mileage?

Thanks.

~Rob.

 

[samotahoe]

they made the switch for a reason, whether it be gas mileage or wear and tear issues. so in any case I would go with the superseded number.

 

[SmokeEater]

Thanks Samo.

I called AC Delco's service center and was told the switch was due to the 41-110 spark plugs being on "national backorder". He said since the 41-110 iridium's has to be used for the 2006 and newer 5.3L, they're suggesting the 41-962 platinum's for 2005 and older 5.3L vortex engines.

I'm not sure I'm buying this since every store I've checked has plenty of the 41-110's in stock and they're within a few cents of the 41-962, so price is not driving it either.

I asked if the 41-110 spark plugs needed to be switched if already installed and he said no.

Does anyone know if the AC Delco 41-962 is the original factory spark plug for the 2000 5.3L vortex?

Thanks.

~Rob.