I have a Magnum RT 5.7L. According to my dealer synthetic oil is fine but you should still change it every 3000 miles. I thought that one of the big advantages of synthetic oil was longer intervals between changes?

Also they said that platimun plugs were fine but still change them at 30,000 miles (they origionally came with regular copper plugs). I thought taht the use of platimun plugs extended the change interval?

Am I getting good or bad advice?

 

with the new oils came new change intervals and the motors now are very high tech and go longer, I have always changed my oil @ 3000 miles regardless of what type of oil I use which is Castrol and I'm using the new syn and I may go to 5k. As far as plugs go they all want you to buy theirs and some are not worth the price or the hype like split fire which are worthless

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when you least expect it, expect it

 

I have a 2006 R/T also with the 5.7 Hemi. I've been running it with synthetic oil since I added the 'hidden hitch' and have been towing a small utility trailer with it. Both dealer and my own mechanic said no problem going 5k between changes even with the trailer. They also both recommended the platinum plugs but also said not to bother with the 'platinum plus' or specialty plugs that user Max Wedge referred to. I changed them out myself at 30K and have not noticed any appreciable difference in performance good or bad. Only time will tell if they live up to their longevity claim.