Gtechniq Long Term Review Part 2: C4 Permanent Trim Restorer

Any vehicle that has been outside for more than a couple years is likely to have issues with the black plastic trim fading and turning grey. It happens gradually so a lot of us don’t even notice any change until it begins to look damaged.

For those of us who take pride in our vehicles’ appearance, having dull, faded trim is unacceptable. You can have the nicest looking paint job in the world but worn out trim will drag the look of your car down fast. The solution is to restore the trim with a product like Gtechniq C4.

This is Part 2 of my long term test of Gtechniq coatings. Just like the other products, I applied C4 Permanent Trim Restorer 2.5 years ago to my 4runner and haven’t touched it since – aside from washing it. If you haven’t yet, make sure to check out Part 1 where I share my experience with Crystal Serum Light and Exo V3 in depth.

Gtechniq C4 Permanent Trim Restorer – What it is and what it isn’t:

There seems to be some confusion out there regarding what exactly this product does. A large part of that is due to its name (which in classic Gtechniq fashion, is rather… long). First off, C4 is a ceramic coating through and through. Much like any other coating, it’s clear, stinks, and causes the applicator to harden once it has cured.

This product is primarily meant to protect your black trim. It just so happens to bring back a nice matte finish in most cases as a bonus. This will protect new trim from fading due to UV exposure while also beading water and making it more difficult for dirt and grime to stick to it. These attributes are further proof that this is indeed a ceramic coating.

Gtechniq C4 does not contain any dyes or fillers that will permanently restore your trim. There is a chance that it won’t bring extremely damaged pieces back to their original finish. With that said, it does do a great job of restoring a fresh finish to most moderately damaged trim.

C4 Permanent Trim Restorer is also not a dressing. There are a ton of those products on the market, and they all fail heavily in comparison. A dressing is an oily substance that sits on top of the surface. Dressings tend to wear off after a few washes and depending on their makeup, can attract dirt and dust.

C4 is a coating that bonds to the trim chemically rather than sit on top. That means it’ll last MUCH longer and feels completely dry to the touch.

How do you know if Gtechniq C4 will improve the appearance of your trim?

Gtechniq has an easy test for this. Take a damp microfiber towel and wipe your faded trim. If it looks better when it’s wet, that’s likely how it’ll look after applying C4. If you do this test and your trim still looks damaged, you’re probably better off looking for a different solution.

How to apply Gtechniq C4 Permanent Trim Restorer

Application for this product is really simple with little to no mess. The most important thing is to clean the trim thoroughly. You don’t want any grease or oils left behind from other products as that will greatly affect the longevity and appearance of C4.

If you’re already certain that the trim is clean, you can skip ahead to wiping it down with isopropyl alcohol, Gtechniq Panel Wipe, CarPro Eraser, or something similar. If you’re unsure of what’s on the surface, I’d recommend using an all purpose cleaner before following up with alcohol.

Gtechniq includes a few applicators in the box but they tend to get chewed up pretty quickly if you’re applying it on rough textured trim (like the bed rails of a pickup truck). An easy alternative is to use a suede cloth like you would when applying a ceramic coating to your paint. You can even cut it down to a similar size as the ones Gtechniq sends if you want to reach tighter areas.

Applying C4 is relatively foolproof. Focus on getting thin, even coverage on the whole surface. It’s important to wipe off any excess product with a towel, especially porous plastic. If you don’t and you’ve laid the product on thick, it can pool in the pores.

Since it’s a ceramic coating, it will crystalize when it cures and form white spots on the trim. If this happens, Gtechniq recommends scrubbing with an all purpose cleaner and a brush then reapplying the C4.

The only other thing to watch out for is getting any excess C4 on any surrounding areas, especially paint. If you catch it when it’s still wet, it’s not a big deal at all. If you give it time to dry and harden though, you’ll be breaking out the polisher.

How long does Gtechniq C4 Permanent Trim Restorer last in the real world?

Despite its name, I don’t believe C4 is permanent. Gtechniq claims it has about a 2 year lifespan. I suppose this could vary depending on the condition of the trim underneath. Badly damaged plastic could start making a comeback sooner than expected.

My experience with the durability of C4 is actually better than advertised. I applied it to the wiper cowl and rear bumper trim of my 4runner 2.5 years ago. Those two pieces were moderately faded – not terrible, but very noticeably dull.

It restored a nearly perfect matte finish that has lasted to this day. It may have faded a bit over the years but it definitely doesn’t look anywhere near what it did before applying C4. Water beading has slowed down though which tells me it’s getting a bit tired. I’ll be reapplying it when I coat the rest of the 4runner.

So no, it probably isn’t permanent. But it did over-deliver in my case, so I have no complaints there.

Where to buy Gtechniq C4

C4 Permanent Trim Restorer is available at most detailing supply stores. You can also purchase it online here. While it won’t necessarily break the bank, it’s certainly more expensive than a regular vinyl/plastic/rubber dressing. This is a situation where you get what you pay for, though.

Gtechniq C4 alternatives

I’m a big fan of this product and it does an excellent job in most cases. But as I mentioned earlier, it might not be the answer to your problem. For one, it’s a bit on the pricey side. In other cases, the trim is too far gone for a coating like C4 to save.

In that case, you’ll want to use a restoration product like Solution Finish. One look at these two side by side and it’s obvious that they’re completely different products. Solution Finish is meant to restore heavily damaged trim. It contains a dye that actually turns the trim black again.

I’m curious if it’s possible to restore the trim with Solution Finish first, then protect it with C4 after. I suppose there could be issues with the C4 bonding to the surface, but it’d be an interesting experiment.

For the budget-conscious detailer, a dressing like Mother’s Back to Black might be better suited. This is a dressing and won’t last anywhere near as long as the other options – but it’s better than nothing. You’ll need to reapply this often and it won’t give the same appearance as the more expensive products either.

Another alternative that we’re seeing become more and more popular is to simply use the same ceramic coating that you put on your paint for your trim too. Some professionals that offer Gtechniq coatings don’t bother stocking C4 and apply Crystal Serum Light or Ultra to a vehicles’ trim instead.

This pushes me further toward a suspicion I’ve had regarding what’s exactly in the bottle, but I’ll leave the conspiracy theories for another day.

Off label uses for Gtechniq C4

If you’re a regular reader on this site, you already know I’m a big fan of finding off label uses for detailing products. While the ideas I had for C4 aren’t technically considered “off label” because it’s all plastic trim, they’re interesting nonetheless.

Use it on plastic trim in your engine bay

Just because it’s hidden under your hood doesn’t mean you can’t coat it with C4. Back when I did all the coatings on the 4runner, I decided to test this on larger flat trim pieces like the panel on top of the rad and the airbox. I used a typical water-based dressing on the rest.

It’s no surprise that Gtechniq C4 lasted a lot longer than the dressing while attracting less dirt and dust. The downside is that you can’t spray it all over the intricate areas that are harder to reach like you can with a dressing. But for larger pieces that are easy to reach, it seemed to work well.

Use it on your fender liners

This tip is more for taller 4×4 vehicles like trucks and SUVs since you don’t see much of the inner fenders on regular cars. Having a nice dark contrast in your wheel wells compared to your shiny paint is one of those things that really makes your car pop.

I was really happy with the way C4 performed on the fender liners of the 4runner. I didn’t have to dress them after every wash – just a quick wipe and they looked brand new again.

Obviously, being constantly impacted with rocks and dirt directly from your tires means it won’t last as long here as it does on say, your wiper cowl. But I got pretty close to a year of awesome results with this which is a huge improvement over using a dressing. It also made it a lot easier to clean dirt and mud from this area. That’s a big bonus.

I wouldn’t necessarily go out and purchase a bottle of C4 for either of these uses due to the cost. But they both come in handy if you have a bunch leftover in the bottle after doing your regular trim.

The final verdict:

In the end, I think Gtechniq C4 is a home run. You have to seriously neglect your plastic trim in order for it to get to the point where C4 can’t help it. In that case, I still think a restoration product like Solution Finish is the way to go.

I also find the name “Permanent Trim Restorer” a bit misleading. Simply referring to this as a “trim coating” is much more accurate.

It’s still going strong on my 4runner although I’ll be refreshing it soon when I detail the rest of the truck. I actually had to use a different car as an example in these before and after pics because the trim on the 4runner still looked too good 2.5 years later. That says a lot.