If anyone is planning to purchase one to four 4-pks of these plugs (recommended by Dale Walker), there is currently an Autolite rebate in affect for up to a total of 16 plugs. I recently purchased two 4-pks from https://www.rockauto.com/en/parts/autolite,XS4303,spark+plug,7212 and promptly submitted my UPD's, rebate form, and my email/online purchase receipt. The rebate for this specific plug is $2 EACH, for a total of a $16 rebate on plugs that cost me $32.07 with shipping, so basically these plugs will have cost me $2.01 each. The rebate offer expires 12/31/2018. https://www.rockauto.com/Images/CurrPromoFiles/Autolite_Rebate_Pads_2018-WEB.pdf