Right now I only do 2 years on my outboard, Denso … year on mower, guess with my 1st XG3614 that could go 2?…
But, road vehicles based on mileage and that tends to stay within 9 months … Don't think I'd want to vulcanize a gasket, LoL … As BrocL used to post … need to get under your vehicle once in a while …