Just to add more fire into the mix - 2004 Mazda 2 DY 1.4 manual. Did an oil change when I got the poor thing and used shop recommended 10w40 oil which then, after the car not really moving for a few months, caused the same tapping noise. We did some digging (I work at a garage) and, knowing that the timing had been done shortly before I got it, decided it was probably the tappets as they hadn't been adjusted when the timing was performed. However my boss, who loves spending all his money on old cars, asked me what oil I used, and I told him, and he told me we should try a thinner oil as the lifters and tappets aren't hydraulic, so the thicker oil was causing them issues. We did a flush and an oil change, new filter, and an additive. Noise gone. For how long? God knows, the car is 20 years old and pushing 130,000 miles, but it doesn't sound like someone poured ball bearings into the engine any more.

TL;DR try thinner oil, like a 5w30 with your next oil change.

 

10W40...Probably not great in the 1.5lt for cold starts.

I'm running a Full Synth 5W40 & was not expecting a challenge, 5W40 is nominally suitable to 50 DegC Ambient, some suggest 5W30 tops out at 30 DegC Ambient.
I can swap to 5W30 Full Synth for the next oil change through the rest of winter, not sure I'm keen to run a 5W30 thru Summer here with multiple days over 45 Deg C.
Detail on HTHS will be important.
5W40 HTHS @ 150Deg C >3.9
5W30 HTHS @ 150Deg C >2.9 or >3.2 depends on the version of 5W30

NOACK evaporation test is also a consideration.

Some say Non Turbo Gasoline Engines Temperatures:
Piston Crown = 204 to 426 DegC
Top of Cylinder Wall = 93 to 371 DegC
Piston Rings = 149 to 315 DegC
Piston Skirt = 93 to 204 DegC
Bottom of Cylinder Wall = up to 149 DegC
Wrist Pin = 121 to 232 DegC
Main Bearings = up to 177 DegC
Connecting Rod Bearings = 93 to 204 DegC
Exhaust Valve Heads = greater than 426 to 538 DegC
Exhaust Valve Stems = greater than 149 Deg C but Less than 426 DegC

Noted, you can plot your own oil combinations:
Widman - Graph Your Oil Viscosity Vs Temp

For my specific readily available "Oil Choice Options", Viscosity Vs Temp Full Synth GTL 5W40 & 5W30, so between 7 Deg C & 12 Deg C cold start there is a benefit to 5W30


The Lubrizol comparison graphing tool is also of interest:
Lubrizol - Relative Comparison Tool of the "Standard ACEA & ILSAC & API Benchmark Tests"

Overlay ACEA2023 A3/B4 & ILSAC GF6 (GF6A for 5W30) for interest, you can put on SP but if you have ILSAC GF6 (GF6A for 5W30) it indicates you exceed API SP.


Rob

 

Hi! I know this post is almost 2 years old now, but did you find any solution?

I am facing with the same problem now and I'm starting to believe it's piston slap. My car had 5w30 in it since new, I tried 5w40 and it seems that it did quiet it down a little. Anything else I tried had no results and data from my engine seems alright in the logs.

 

Welcome to the forum

As you are in Romania your specif model mazd may be different from the opriginal authors of this thread.
Advise.... start your own thread.
While you may think it is the same and based on your guessing its more then likely NOT.
When you start your thread make sure to add the basic information about your Mazda..
While most videos are useless try making one anyway but keey the video on the target location of the noise.

Repeat you should start your own thread.