well i got a new question i have about half a case of the oil i was running in my 3.9l and it is castrol 20w-50 my dad swears by it for some reason and my r/t accordin to the service sticker is running valvoline 10w 30 i would like to use royal purple snythetic but my question is would it be ok to use what left of the oil i have and then change to the snythetis or should i just make the swap the first time and also will snythetic oil cause leaks if it hasnt been used in the engine before? i know this ones lengthy but any help is greatly appreciated
You need to use a synthetic blend before you can use a full synthetic. Your supposed to do a change, run a blend for a few miles, do another change and run the blend again. I've heard real oil and synthetic oil aren't truly the same density, so they won't mix right.
This may be an old mechanics tale, but I'm pretty sure thats why they sell synthetic blend.
well i decided to find out today so i called summit racing and they told be in a nutshell that switching to a snythetic is fine as long as u dont have any leaks prior and to run the suggest weight of the manufacturer and if u switch to snythetic that u cant switch back to conventional oil due to the engine "getting used to" the viscosity of the snythetic oil so i plan to buy royal purple probably this weekend and one more question what is the suggested oil for my 99 r/t i will probably look under the hood but i cant remember if is actually tells u so yeah thanks for all the replies