i have a 2004 nissan maxima i have taken very good care of this car synthetic oil the whole works yet between 15 to 25 you can hear what sounds like the valves you dont hear it before or after and i dont understand why so much for synthetic oil
I doubt if it is related to synthetic or other oil. Do you have any CEL’s?
You only hear it between 14 & 25 MPH? How long has it been doing this? Did it start up all at once, or did it start with very little noise and it is now getting louder?
Is it related to RPM or MPG? Try going to the next highest gear and see if you get it at a lower speed or the same speed.
Any other issues you did not note?
Just for fun, get under there when it is cool check out the exhaust system and heat shields. Anything loose?
I wouldn’t normally identify this with a lube related issue. It’s only present at a given range of reported (gound?) speed. No mention of it with the engine under no load (not in gear). I mean, it’s surely possible with VVT and cam phasers and whatnot, but it’s not first on the list of likely suspects.
The exhaust leak was a good suggestion. Not always present under no load, exacerbated under load, and (potentially) drowned out at a given road speed. These usually start off with quieting down as the exhaust heats up …then progress to full time from the exhaust gases making the leak worse.
A rag over the tail pipe, held with sufficient force, while someone listens up front might show the leak point (if it exists).
You are using 91 octane or better in this car correct? The Nissan VQ is pretty sensitive to low octane.