Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I am getting my elderly neighbor's mower ready for spring. The mower is a Toro Recycler model 20023. The current spark plug is a champion # RJ19LM. I have a champion # J19LM. Could I use this plug?  I believe the "R" on the current plug refers to resistence and is designed to have less interference with electric appliances, noteably TV a's and radios. Does this mean that the non "R" plug will likely cause interference? What are your experiences with non "R" plugs in your OPE's. Thanks.