So, I have a '93 Del Sol my roommate and I picked up during covid. We had the intention of fixing it up for amateur racing and learning to work on cars. The car ended up sitting for almost three years because our work situations changed and we ended up not doing anything with the car until late 2024 when my, at the time, daiky drivet got totalled in a accident. Instead of doing the smart thing and getting another normal daily, I decided to put all the insurance money towards fixing the Del Sol. We spent a ton of money on getting the card registered and titled, fixing all the suspension components, brand new coilovers from Godspeed racing, and steering components, replacing the clutch, replacing the old and leaking AC hoses (which still leaks somewhere else), removing the ancient fiberglass body kit because it was falling apart, replacing the speakers, replacing the rusted out exhaust and stock headers with a nicer stainless steel 4-2-1 header and skunk2 exhaust. The ECM failed at some point so a new P28 had to be sourced and then modded to work with a manual transmission (just changing out some resistors). The old air intake got pulled out and replaced with a cold air intake and cone filter, new battery because the old one just died and refused to take a charge. We also replaced the old, oversized rims and super stretched tires with Motegi racing 15" aluminum rims and appropriately sized Toyo all weather performance tires. All new fluids, new clutch slave cylinder, new fuses, and four wheel drilled and slotted disc brake kit from stoptech.

That pretty much brings us to where we are today. The engine had low compression when we first got it running back in 2022 but we didn't really have time to do anything about it then. Flash forward to 2026, the same problem still exists. Cylinders 1, 2 and 4 measure about 90psi and cylinder 3 measures about 30psi when doing a compression test. The piston rings are definitely bad but the uncomfortable question is whether or not the cylinder sleeves are also damaged, particularly on cylinder 3. If time wasn't a constraint, resleeving with new cast iron or even ductile steel sleeves isn't a huge issue. The problem here is that its my daily so I need transportation Monday thru Friday. We don't have time to just take X amount of time across a few weeks to bumble around and figure it out. I also don't have the money to just outright pay a shop to do it because now its not only parts but labor cost too.

Alternatively, we found a good condition D16Z6 engine for $2000 shipped, which would be a good option if it wasn't for the fact that I don't just have that kind of money just sitting around. It would expidite the issue of fixing the engine by just replacing it then we can just refurb the old engine whenever we have time.

The third option, much more painfully, is letting the car go and selling it to someone else who does have time to work on it and dedicate the time and money it needs to get up and running properly. I'd rather not do that option because I'll never see a dime of what I spent already. I could take all my parts off and put the ones that were on the car back on but I don't have the original brake kit anymore because it was in atrocious condition, the exhaust the car had before (which wasn't the factory exhaust anyways) was rusted and leaking so it got tossed out. I have the old coilovers but two of them are leaking so that's not great. It doesn't have bumper covers and it doesn't have the facia for the trunk because the one that was on the car isn't the factory one and removing it was the only way I could mount the license plate. Its the sunk cost fallacy right? I'm this far in, I don't want it to feel like I wasted time and money just to be at square one again.

Until I can get the engine worked on, I'd like to do everything possible to extend the life it has and prevent some catastrophic from happening, like throwing a rod or a piston and valve deciding they want to be best friends. I've been using very high quality fluids because I'm paranoid but its also what I did with my daily. Yeah, that was just a '15 Ford Focus hatch but I still paid extra to use better oil and fluids, periodically using Seafoam with a tank of premium to make sure the injectors were cleaned and not clogged.

So yeah, I'm using Motul Dot 5.1 Brake fluid for the brakes and for the clutch, Royal Purple Syncromax for the transmission, Royal Purple HMX High Mileage 5w-30 for engine oil.

I know the responsible thing to do is just replace the piston rings but I don't have time to do that, I don't have the money on hand to have a shop do it either. I just want to know if there's any additives I can use to limit how much additional wear the engine has to deal with until I have enough money set aside to get the new engine.

 

Maybe another option is to search car-part and gamble on an engine from a local salvage yard. Most of the yards around me want you to call for pricing, but the ones that do list a price are asking $800 to $1200 for a D16Z6.

Try to find a listing with photos and look for one that shows a wrecked car. Avoid the ones showing a good body. If it's in the salvage yard with a good body, then it most likely taken there because it has a bad engine.

 

Since it sat for so long could the low compression be from stuck rings? Or maybe carbon up valves? You could do a leak down test to verify if it's valves or rings.

I've been doing a lot of research on oils and so far the Valvoline Restore & Potect has caught my interest, from the many videos and lab testing done looks like a good oil to get piston rings unstuck.

Not sure where you live but theres a junk yard near me that still has a few d series engine available called Yonke Auto Parts in 1-10 on the Texas New Mexico border. I'll post the number if anyone is interested, not sure on condition of engines but might be good cores. (915) 779-9999

 

My advice would be to not sell the car. In the future you will regret it when things aren't as tight and you've already put so much work into it.

You don't necessarily need a great condition engine to swap in, just one that runs. You can get one from a yard for way less than $2000 if it's just to throw it in and drive while you work on the current engine.

Alternatively, you could buy an even cheaper engine that needs a rebuild and work on that before swapping it into the car.

Good luck whatever you decide and hope you get the car to the point you want it so you can enjoy it.

 

Yeah, I spent the last part of my work day yesterday browsing marketplace. The idea of selling the Del Sol kinda went out of the window. There's not many Del Sols available in the Austin area but most of them are in similar or worse condition. There's one with a pretty decent condition body and interior but bad engine that doesn't run and they want $2,500 for it. Even in the condition we got our Del Sol in, it did run and drive even though it was in rough shape. And your right, if I did sell the Del Sol now, I will regret it. I'm going to exhaust all other options first before considering that one.

So, its interesting that you bring up Valvoline Restore & Protect. Its one of the products that was served to me when I was looking for products and additives I could try that may help my engine, or at least prevent it from getting any worse. I'm certainly curious and willing to try it out. I have another product I should be getting in today called Restore Engine Restorer. Project Farm tried it out around 8 years ago and showed that it did improve the compression of a old tractor engine as well as improve the start and idle. He did a follow up a year later and showed that the improvement did last. I'm going to try that product out with my current oil and see what happens with, say, a week or so of driving. If nothing happens or things get worse, oil comes out and Valvoline goes in to see what happens.

I've called a ton of different salvage yards and used parts dealers around Austin, apparently people like using D16Z6s for motorsports. No one really has any. Even Y7 and Y8s aren't really available. There's a pick and pull that has two Civics in the 1993 to 1995 range that I'm gonna go check out if they have useable engines this weekend. Finding a replacement engine is shocking just as difficult as trying to locally find a P28 ECM. xD

 

The Valvoline R&P oil seems to work in my experience. I've been using it for ~18 months in my 3 cars and in my wife's daily driver, all of which are Honda's. The lowest mileage car has 167k miles on it and the highest is at 342k. I've noticed that oil consumption has reduced by the 2nd oil change, so it does seem to free up stuck rings.

 

Ok, so, new development. Some tools I ordered yesterday arrived (Yay amazon prime). I now own a compression tester and a borescope. When I originally did the compression test, this was when we first got the car running after it having sat around since 2022, this would have been around 2024. Because I sent my roommate the compression readings in discord, I know the exact numbers. From left to right, it measured #1 - 90psi, #2 - 95psi, #3 - 35psi, #4 - 85psi. I just finished doing a compression test on all the cylinders and these are what I got. Left to right, #1 - 155psi, #2 -145psi, #3 - 150psi, #4 - 145psi. The only other thing we did to the engine back in 2024 was replaced the valve cover gasket because it had a active and somewhat significant oil leak. The engine leaks oil from a lot of places but that one was much more than others. Either, since starting to drive the Del Sol on and off mid-2025 and actively since March 2026, driving the car around with Royal Purple and periodically using Seafoam with a tank full of premium gas fixed the low compression issue by getting rid of a bunch of caked on carbon and re-lubricating the piston rings OR the fact that I have to drive in 4th gear at around 5000rpms to hit 80mph on the toll ways broke off a bunch of carbon and fixed things on its own. Whatever the reason, compression is higher now than it used to be. From what I can find online, the compression read can be anywhere from around 140psi to as high as 200psi once the engine is at operating temps. So, it seems that whatever is wrong and causing power loss exists else where.

I did still take a video of inspecting cylinder 3 with the borescope since that was the cylinder that was previously significantly low. Maybe someone else can see something I didn't. The cylinder walls seem ok other than some pitting, probably just from age and use. The only thing I really noticed was the unusual pattern of carbon buildup, probably implying that its been flaking off over time, and the fact that there's oil (probably) sitting on the piston, meaning that oil is seeping into the piston from somewhere. My only theory as to why cylinder 3's compression was unusually low is maybe that the intake or exhaust valve may have been slightly stuck open due to carbon buildup. It wasn't open enough to cause a problem with the piston but open enough to give pressure a way out and prevent proper combustion.

 

Glad to hear the compression seems to be okay now Can you further describe what is making it seem like there is a loss of power?

I've recently gone through and livened up the Z6 in my del sol. It went from feeling like it was really struggling to now being pretty healthy. The main factors were removing the clogged catalytic converter, adjusting (and slightly advancing) ignition timing which I now run only 93 octane gas, ran fuel system cleaner and change the fuel filter, new spark plugs with proper gap, and cleaned the throttle body.

 

So, power loss occurs when going up hills or on tall overpasses in 5th gear and engine drops rpms despite throttle being wide open. In 4th, this doesn't happen but rpms also don't climb on hills or tall overpasses. Over flat ground, 4th does gain rpms but not rapidly and 5th gains rpms very slowly. (I.e. going from 70mph to 80mph in 5th takes over 30 seconds on flat ground)

The cat got removed and replaced with a resonated test pipe. Last time I ran a fuel system cleaner was around February/March 2026. I can get a can of seafoam and put it in on my next fill up, that's not a big issue but I don't think its an injector issue. My throttle body could use a bit of lube but the last time I checked it (about two months ago) it didn't seem particularly dirty.

 

Sounds normal for a slow Sol lol! Make sure all your tune-up stuff is done - plugs, wires, cap, rotor, fuel filter, pcv, etc.

 

To be honest, this sounds like pretty normal driving characteristics of a D16. They don't make much power outside of VTEC, so you have to downshift to get over 5000rpms climbing hills etc.

I would check ignition timing, replace fuel filter and do a valve lash adjustment. Outside of that, with those compression numbers it should be running just fine.