Hi all. First post here. I'm looking for some guidance since I'm new to maintaining my cars performance and everything. Previously I had the maintenance done by my mechanic.
A little back history on my current car,
Honda Civic EXI Prosmatec 2004 (D15Y3 engine 1.5L), odo is around 106,000KM -- somewhere around 70,000 miles). I do not know the previous service history of my vehicle. My best guess is that the previous owner used a shitty 5W-30 oil, and the ATF is still pink, but for the most it's lost its bright red colour. The coolant is brown and my guess is that he used distilled water and not the proper premixed radiator coolant, which caused rust and corrosion. And to top it off, he used CNG in the car, rather than using Petrol.
Anywho, I made a list of oils and lubricants I'll be using from Liqui Moly. Please suggest if I should do any changes.

Engine Flush Plush 300ml
Synthoil High Tech 5W-40 4lt
Cera Tec 300ml
Fuel System Treatment 300ml
Honda Genuine Oil Filter 15400-RAF-T01
Radiator Cleaner

 

I don't know how he used CNG, since its an entirely different fueling system (from tank to fuel rail its entirely different and managed different in the ECU as well). The brown liquid in your coolant could also be a sign of a blown head gasket, which is common in this generation of D-series engine.

 

Yeah. But in the next week, the lockdown will be lifted and I want to get over with the seal replacement job, as my main seal, and rear distributor seal is leaking, so is my oil pan seal🤷‍♂️. I'll have my engine tuned by having the tappets adjusted and my ignition coils inspected. In the end, im going all out with Liqui Moly products, since I love this car. I want it to be smooth and the engine to be sound when driving. My vehicle sounds like a tractor when i start it in the morning to make sure the battery doesn't die on me.

 

Your engine doesn't have those.

Coil over plug assembly with no distributor, and an overhead cam setup with rollers on the rockers.

 

Wait what? What even? All of the mechanics to whom I've showed the leaks to, all of them said that the main seal and gear seal is leaking.
If this is case that my engine doesn't have those, where the flub is the oil leaking from. It's definitely the engine oil which is leaking. It may be the seal around the oil pan but I'll have to get it checked soon.

 

Take a picture of what you're referring to. But, unless you have a different engine then previously mentioned, you don't have a distributor.

 

They were likely referring to the rear main seal which lives between the engine and transmission and can leak oil when it is worn out. The valve lash can be adjusted, but I wouldn't do it unless there is noise coming from the valvetrain.
A lot of info if you use the search function here. Also more elsewhere on the internet if you google it.
Honda D15B engine (D15A, D15Z, D15Y) | Reliability, tuning . . https://en.wikipedia.org/wiki/Honda_D_engine#D15Y3
Liqui Moly are good lubricants, as are Royal Purple and AMSOIL. Brand doesn't matter so much as long as its A: from a somewhat reputable company, B:is the correct weight and C: full synthetic as much as possible.
I'd recommend just some routine maintenance like spark plugs, oil/filter, air filter, coolant flush and a very thorough car wash and detail. My car usually runs better after I wash it.