When it comes to engine repairs, especially oil leaks, there’s a right way and a wrong way to seal components. A recent job at our workshop highlighted this in a big way—and it all comes down to one common mistake: using RTV (Room Temperature Vulcanizing silicone) instead of proper gaskets.
A 5 Year Oil Leak Finally Traced
We had a customer travel from interstate to get to the bottom of a persistent oil leak that had plagued their vehicle for over five years. They’d been to multiple workshops, spent thousands, and still ended up with the same leak every time.
By the time the vehicle reached our shop, we expected to find something unusual. What we uncovered, however, was worse than expected.
The engine had clearly been apart before, but instead of the proper gasket, the entire sump had been sealed using only RTV. Not just a thin bead either. There was so much silicone applied that it had squeezed out inside the engine and posed a risk.
Why is this a problem? RTV can break off in chunks and end up in critical oil galleries or block the oil pickup, leading to oil pressure issues or even catastrophic engine failure.
This isn’t just a cosmetic issue, it’s a mechanical disaster waiting to happen.
Why You Should Always Use a Sump Gasket
Manufacturers design gaskets for a reason. They provide an even seal under clamping pressure, allow for thermal expansion, and are built to last under the heat and oil conditions of an engine bay. RTV has its place, such as joining corners or assisting with sealing certain surfaces—but it should never be used as a full substitute for a proper gasket.
In this case, the engine had to come completely out just so we could clean up the RTV mess and do the job properly. That’s not normally required for a sump gasket, but we weren’t about to risk letting this one leave the shop still full of silicone.
Once the engine was on the stand, we:
- Removed the excessive RTV
- Replaced the sump gasket
- Resealed the timing cover properly
- Cleaned all mating surfaces thoroughly
- Reassemble the engine using the gasket and a thin amount of RTV
The difference? No more leaks, no more guesswork, and no risk of RTV causing internal damage.
Whether you’re a DIYer or a licenced mechanic, remember this:
RTV is not always a direct replacement for gaskets. Using it incorrectly can cause more harm than good. When you’re dealing with oil leaks, especially persistent ones, it pays to do it once, and do it properly.
If your vehicle has been leaking for longer than it should, or you’ve been given the “just seal it with silicone” treatment before, get in touch on 9987 2818 or book online. We don’t guess. We diagnose.
