Oil change and new ticking

Lance Unibagger

Lance Unibagger

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Joined
May 27, 2025
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27
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Las Vegas
Hello, I am exhausted from reading post after post regarding ticking noise, and I am not sure what to do next.
I purchased the Jeep with 70k and no ticking.
Changed the oil at 75k and now it ticks when fully warmed up.

Oil is Castrol Edge fully synthetic high mileage.
Dash oil pressure at idle is 20psi when fully warm.

I used the old screwdriver/stethoscope on the valve cover and it sounds smooth with slight tick.
From the top of the catalytic converter the tick is louder.
The ticking sounds more pronounced from under the Jeep than with the Hood open and is more noticeable from the drivers side.
No change in driving performance, no smoke from the tailpipe either.

I just have a hard time believing that in 5k a rocker arm or lifter has gone south and the no noise when cold is puzzling me.

Any thoughts or suggestions are very much appreciated.
 
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Lance Unibagger said:
Maybe super far fetched, but I wonder if the dealer knew about the ticking and put in an additive or heavier oil to sell the vehicle.
Click to expand...

That's where I was going too. My buddy did that with his 99 WJ. Put a whole bottle of that Lucas stuff in it before he sold it and you'd never known it had a knock.
 
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tJKrider said:
You could drain the oil and refill with a heavier weight and see if that changes or eliminates the tick.
Click to expand...

So here is my thought on replacing the oil, I did the oil change and the engine has a tick, but not at start up and not when cold; isn't 5w20 5 weight cold and 20 when hot? If it was the oil viscosity it should chatter at cold start correct, or am I missing something here?

I did read about ZDDP (I think that's it) and some oils do not have it and some have more and the lack of ZDDP can cause ticking.

I feel I might rabbit hole myself into craziness, but don't want to spend the money on a new lifter and rocker set if I don't have to and the job appears to be a pain.

I am going to see if I can get the cat out of the way and see if it is an exhaust leak.

Thank you for giving it some thought to help me out - much appreciated.
 
Lance Unibagger said:
So here is my thought on replacing the oil, I did the oil change and the engine has a tick, but not at start up and not when cold; isn't 5w20 5 weight cold and 20 when hot? If it was the oil viscosity it should chatter at cold start correct, or am I missing something here?

I did read about ZDDP (I think that's it) and some oils do not have it and some have more and the lack of ZDDP can cause ticking.

I feel I might rabbit hole myself into craziness, but don't want to spend the money on a new lifter and rocker set if I don't have to and the job appears to be a pain.

I am going to see if I can get the cat out of the way and see if it is an exhaust leak.

Thank you for giving it some thought to help me out - much appreciated.
Click to expand...

Oil pressure will play a role in this as well.

Multi viscosity oils are complex. They start out with a base oil that is the same as the "Winter" weight rating. So 5W-20/30 begin as an SAE 5 oil and then are chemically formulated to act as a 20 or 30 as the temperature increases. The reality is that they can't replicate the higher weight oil at all temperatures. My guess is that with 5W20 and under 100°C oil temp the viscosity may be too low vs. a true 20 weight oil. If they used 5W30 at the dealership that may have provided just enough added viscosity to surpass the temp/pressure "tick" threshold.

Just a hunch...

Lance Unibagger said:
From the top of the catalytic converter the tick is louder.
Click to expand...

I like your theory of an exhaust leak. Those can have a definitive ticking quality to their sound as well.
 
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