What is the Best RTV for Oil Pans?
Oil pans play a crucial role in engines, holding the oil that lubricates and cools your motor. However, over time the gasket between the oil pan and engine block can wear out or get damaged, allowing oil to leak. Replacing just the gasket is difficult, so many mechanics recommend using an RTV gasket maker to reseal the oil pan. But with different types of RTV available, how do you choose the right one?
This guide covers everything you need to know about picking the optimal RTV or gasket maker when resealing an oil pan. We’ll compare popular RTV sealant options, look at application tips, and make recommendations for the best oil pan gasket products. Read on to learn which RTV is ideal for your engine!
What is RTV?
RTV stands for “Room Temperature Vulcanizing” silicone. It’s an adhesive sealant that starts as a paste or liquid but then sets and “vulcanizes” at normal room temperature as it cures.
RTV is flexible when cured, allowing it to absorb vibration and expansion between mating surfaces. It also provides an exceptional seal against oil, coolant, fuels and other liquids. This combination of flexibility and sealing power makes RTV a go-to solution for sealing components in engines and industrial equipment.
Some key advantages of RTV gasket makers include:
- Sets up at room temperature – no special tools or heat required
- Won't leak, crack, or shrink like pre-cut gaskets can
- Conforms to irregular surfaces for a reliable seal
- Vibration-proof when cured
- Resists automotive fluids like oil, gasoline, coolant etc.
With these benefits, RTV silicone is the top choice of many mechanics when resealing an oil pan or valve cover. But not all RTVs are created equal…
Blue RTV vs Black RTV Silicone – What’s the Difference?
The two most common types of RTV sealant are blue RTV and black RTV. What sets them apart? Here's a quick rundown:
- Blue RTV – Designed for sealing components exposed to coolant and high temperatures like cylinder heads and water pumps. Not recommended for oil pans.
- Black RTV – Made for surfaces exposed to oil like valve covers and oil pans. Black RTV resists breakdown from oil exposure better than blue.
So for an oil pan gasket, a black RTV silicone formulated for oil resistance is the best choice. Blue RTV can work in a pinch but may eventually fail. Always check the label to confirm the RTV you’re using is designed for oil contact.
Now let’s look at some leading oil pan RTV products to consider…
Top 3 Black RTV Sealants for Oil Pans
#1. Permatex 82180 Ultra Black Maximum Oil Resistance RTV Silicone Gasket Maker
Permatex Ultra Black is a sensor-safe, non-corrosive RTV gasket maker designed for superior adhesion and sealing on oily surfaces. It offers long term durability and retention of flexibility, replacing pre-cut gaskets or serving as a reliable gasket sealant.
Key Features:
- Non-corrosive formula safe for sensors
- Withstands temps from -65F to 500F
- Resists oils, transmission fluid, coolant
- Remains flexible without hardening
- Bonds steel, aluminum, iron, plastic
With exceptional oil resistance and flexibility, Permatex Ultra Black is an ideal RTV silicone for permanent, leak-free oil pan repairs.
#2. Permatex 82194 Ultra Grey Rigid High-Torque RTV Silicone Gasket Maker
Permatex Ultra Grey is an OEM-approved RTV designed for high vibration and torque applications. It offers maximum oil and fluid resistance.
Key Features:
- Made for high-torque, vibration environments
- Exceeds OEM performance standards
- Withstands temperatures from -65F to 500F
- Non-corrosive and low odor
- Resists engine oils, coolant, transmission fluids
Ultra Grey provides superior sealing for oil pans and gaskets under high heat and vibration. It’s an excellent RTV for import engines and performance applications.
#3. Loctite 518 Gasket Maker Flange Sealant
Loctite 518 Flange Sealant is a non-corrosive RTV gasket maker ideal for flanged aluminum, steel and iron surfaces.
Key Features:
- Non-corrosive formula safe for metal
- Fills gaps up to 0.050 inches
- Flexible seal won't crack or tear
- Easy to apply putty-like consistency
- For water pumps, thermostat housings, transmission pans
With its putty-like consistency and flexibility, Loctite 518 adheres well for making instant seals on flanges. It’s a solid RTV option for oil pans and gearboxes.
How to Use RTV Sealant on an Oil Pan
Using RTV to reseal an oil pan isn't difficult, but proper preparation and application are key. Here are general directions:
Supplies needed:
- RTV sealant (black silicone formulation recommended)
- Gasket scraper
- Sandpaper
- Cleaning solvent like brake cleaner
- Applicator like a caulking gun or small spatula
Step 1: Remove Old Gasket
Thoroughly clean away all residue and debris from the old oil pan gasket using a gasket scraper and solvent cleaner. Any remaining material can prevent the RTV from sealing properly.
Step 2: Sand Surfaces
Lightly scuff the oil pan and engine block sealing surfaces using 200-400 grit sandpaper. This helps the RTV adhere and bond tighter.
Step 3: Clean and Dry
Wipe down the surfaces with solvent cleaner to eliminate any oil or contaminants. Make sure mating surfaces are completely dry before applying RTV.
Step 4: Apply RTV
Run a 1/4” bead of RTV sealant around the edge of the oil pan flange. Use a caulking gun for the easiest application.
Step 5: Install Oil Pan
Lower the oil pan into place immediately after applying the RTV. Some sealants set quickly.
Step 6: Torque Bolts
Tighten the bolts to torque spec in a criss-cross pattern. Don't over tighten!
Allow the recommended curing time before filling engine with oil. Check for any leaks before driving the vehicle. Re-torque bolts after test driving if needed.
And that’s all there is to it! With the right preparation and using a quality RTV silicone like the ones above, you can easily reseal an oil pan leak in your garage. Be patient during curing and testing to ensure a permanent, leak-free repair.
Conclusion
Fixing an oil pan leak with RTV silicone is a convenient, affordable DIY repair. Permatex Ultra Black, Loctite 518 Flange Sealant, and Permatex Ultra Grey are top recommendations for oil pan usage. Always use the proper supplies and prep steps for optimal adhesion and sealing. Allow adequate cure time before driving the vehicle. Resealing with the best RTV for oil pans creates a durable repair that will permanently stop leaks.
Frequently Asked Questions
Q: What is the difference between GREY and black RTV silicone?
A: Black RTV is designed for oil resistance, making it the optimal choice for oil pans. Grey RTV withstands higher temperatures but may eventually fail when exposed to oil. Always use an oil resistant RTV on oil pans.
Q: What is the best sealant to use on a oil pan?
A: Look for a black RTV silicone specifically formulated for oil resistance and engine use, like Permatex Ultra Black or Loctite 518 Flange Sealant. Avoid general purpose, hardware store clear or red RTV sealants.
Q: What RTV is good for oil?
A: Black RTV silicones resist oil breakdown the best. Top oil-safe choices include Permatex Ultra Black, Loctite 518 Flange Sealant, or Permatex Grey for extreme temps. Only use RTV sealants designed for oil contact.
Q: What is the best gasket for oil pan?
A: Pre-cut rubber gaskets can work but may eventually leak. Most mechanics recommend using a 1/4″ bead of oil resistant black RTV sealant as a more permanent, reliable oil pan gasket. It seals irregular surfaces and won't crack over time.
Q: Can I use RTV instead of a gasket?
A: Yes, black RTV silicone can completely replace a traditional pre-cut gasket. Make sure to prep the surfaces properly and apply a continuous 1/4” bead following the sealing surfaces. Allow proper cure time before reinstalling oil.
Disclaimer:
- This article contains Amazon affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you.
- This article is for general informational purposes only. Consult mechanic's recommendations and repair manuals for your vehicle.
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