Which RTV Gasket Maker Brand Wins?
We compared 13 rtv gasket maker options head to head. Mopar came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Mopar
Price shown in test: $13 for 3 oz (spoken as '4.33 cents per ounce', unit likely should be dollars since 13/3=4.33; the number itself is mathematically consistent)
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Toyota
Price shown in test: $20 for 3 oz ($6.67 per oz). Note: this exact price and per-ounce figure is spoken word-for-word identically for both Toyota and John Deere in immediate succession, a likely caption duplication; see videoNotes.
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The measured results
Every number below is read straight from the test. Scroll sideways to see all measurements. Products are listed in the order they finished.
| Product | Test Cup Weight | Tensile Strength | Cured Area | Flex Adhesion Test | Hardness | Pressure Test | Gasoline Resistance |
|---|---|---|---|---|---|---|---|
| 1Mopar$13 for 3 oz (spoken as '4.33 cents per ounce', unit likely should be dollars since 13/3=4.33; the number itself is mathematically consistent) | 20.28 g | 75.6 lb, 73.4 lb, 74.6 lb; best tensile result of any brand at that point in testing, very consistent | quite a bit of uncured gasket maker remaining in the center of the PVC end cap at 72 hours (no mm figure given for this brand) | 4.8 lb, second place behind Versachem, described as very good flexibility and strength | 24 (durometer) | just over 1,000 PSI in the main narration, explicitly restated as 1,010 PSI in the capstone recap sentence; best combination of tensile strength and hardness of any brand tested | PASSED, held up just fine after 2 hours of E10 exposure |
| 2Toyota FIPG (Formed In Place Gasket)$20 for 3 oz ($6.67 per oz). Note: this exact price and per-ounce figure is spoken word-for-word identically for both Toyota and John Deere in immediate succession, a likely caption duplication; see videoNotes. | 15.51 g, very close to AISIN's 15.48 g | 66.8 lb, 74 lb, 76 lb; outperformed AISIN, fully cured across the entire PVC end cap surface | came out on top of the separate cure-completeness leaderboard, fully curing the test piece | 2.8 lb, fourth place in this category (a little stronger than AISIN's 1.8 lb) | 19.5 (durometer), cross-referenced tensile strength of 72.3 lb | 640 PSI before a massive blowout | FAILED, did not survive the 2 hour E10 exposure test |
| 3Honda Bond$17 for 1.9 oz (spoken as '8.95 cents per ounce', unit likely should be dollars since 17/1.9=8.95) | 20.93 g | 101.2 lb, 91.4 lb, 89 lb; best tensile results of any brand tested, described as a very impressive, commanding lead over Mopar | 8.7 mm in the separate cure-completeness leaderboard, behind Toyota's full cure | 3.6 lb, third place, performed better than average | 41 (durometer), cross-referenced tensile strength of 93 lb | began losing pressure at 380 PSI | FAILED, no longer bonded after the 2 hour E10 exposure test |
| 4Versachem Mega Gray$9 for 3 oz, same price point as JB Weld and Pro Seal | 21.97 g, very close to Permatex Ultra Gray | 63.8 lb, 73.6 lb, 68.6 lb, average 68.7 lb; moved into the lead over Permatex Ultra Gray at that point in testing | still a pretty large uncured area at 72 hours (no mm figure given) | 5.2 lb, best result of any brand in this category ('Versa Kim came out on top') | 24 (durometer), cross-referenced tensile strength of 67.8 lb | 790 PSI, a strong result though ultimately fourth-best behind Mopar, JB Weld, and Pro Seal in the capstone recap | PASSED, held up just fine after 2 hours of E10 exposure |
| 5JB Weld Ultimate Gray$9 for 3 oz ($3.00 per oz) | 18.17 g, about 2 g less than Permatex Ultra Gray | 49.8 lb, 49 lb, 51.8 lb; less than 3 lb of variance across the three samples | still pretty gooey in the middle at 72 hours; cured-area width 6.26 mm, slightly wider than Permatex Ultra Gray's 5.79 mm | 2.6 lb, more flexibility than Permatex Ultra Gray, released slowly | 15.5 (durometer), the softest of the lineup | 875 PSI, second-best result of any brand tested behind Mopar | PASSED, held up just fine after 2 hours of E10 exposure |
| 6Pro Seal Gray RTV Silicone Instant Gasket$9 for 3 oz ($3.00 per oz) | 15.78 g, about 7 g less than Permatex Ultra Gray and Versachem | 55.2 lb, 44.4 lb, 45.8 lb, average 48.5 lb; almost completely cured despite the lower tensile strength | 11.38 mm in the separate cure-completeness leaderboard, described as performing about the same as Toyota's fully-cured result | 0.8 lb, the weakest result of any brand tested, did not demonstrate as much adhesive strength as other brands | 17 (durometer), almost as soft as JB Weld | 820 PSI, third-best result of any brand tested behind Mopar and JB Weld | FAILED, did not survive the 2 hour E10 exposure test |
| 7Permatex Ultra Gray$9 for 3.5 oz (spoken as '2.57 cents per ounce', unit likely should be dollars since 9/3.5=2.57) | not tested | 66.4 lb, 54.2 lb, 66.4 lb; described as pretty consistent results, first product tested | 5.79 mm cured-area width at 72 hours; center of the PVC end cap still not fully cured | 2.4 lb, let go quickly with little flexing or bending | 35.5 (durometer) | 125 PSI before giving up | FAILED, destroyed by the E10 gasoline after 2 hours |
| 8Permatex Right Stuff$17 for 3 oz (spoken as '5.67 cents per ounce', unit likely should be dollars since 17/3=5.67) | 22.17 g | 58.4 lb, 65.4 lb, 56 lb, average 59.9 lb; performed better than some other brands despite an uncured section | a section not quite cured at 72 hours (no mm figure given) | 2.4 lb, very close to Permatex Ultra Gray's result, quick release | 43 (durometer), the hardest gasket maker of the lineup | 135 PSI, about 10 PSI better than Permatex Ultra Gray | FAILED, described by the narrator as 'the wrong stuff for gasoline exposure' |
| 9AISIN$19 for 3 oz (spoken as '6.33 cents per ounce', unit likely should be dollars since 19/3=6.33) | 15.48 g | 58 lb, 56.8 lb, 60.4 lb; performed about the same as Permatex Right Stuff, very consistent | performed about the same as Permatex Right Stuff for curing (qualitative, no mm figure given) | 1.8 lb, quick to let go, though almost fully cured across the test area at the time of this test | 18 (durometer), cross-referenced tensile strength of 58.4 lb | began leaking at 520 PSI, topped out just over 600 PSI | FAILED, destroyed by the E10 gasoline |
| 10John Deere$20 for 3 oz ($6.67 per oz). Note: this exact price and per-ounce figure is spoken word-for-word identically for both Toyota and John Deere in immediate succession, a likely caption duplication; see videoNotes. | 17.39 g | 33 lb, 31.6 lb, 28.8 lb; gave up earliest of any brand tested, though results were internally consistent | small area still not fully cured even at 72 hours; 8.37 mm in the separate cure-completeness leaderboard, the widest uncured area among the brands given a specific figure there | did not make it off of zero pounds before letting go, the weakest result of any brand tested | 16 (durometer), cross-referenced tensile strength of only 31 lb, the softest and weakest combination in the lineup | experienced a massive leak at only 200 PSI, the worst main-test pressure result of any brand | FAILED, destroyed by the E10 gasoline |
| 11Yamalube 5$12 for 2.5 oz ($4.80 per oz) | not tested | 11.4 lb, 10.2 lb, 12 lb, average 11.2 lb; the weakest tensile results of any brand tested, though it did fully cure across the entire PVC end cap surface on the second test piece | not tested | let go very quickly at less than 1 lb, among the weakest results of any brand tested | not tested | began leaking very quickly at around 20 PSI, the worst result of any brand in this test | FAILED, 'the gasoline was just too much for the yamalube' |
| 12Loctite Gray$9 for 2.7 oz (spoken as '4.33 cents per ounce'; this does not match the brand's own stated bulk price, since 9/2.7=3.33, not 4.33 - a likely genuine number garble, distinct from the unit-word issue seen elsewhere in this video; see videoNotes) | 21.74 g, very close to Versachem | 39 lb, 38.4 lb, 38 lb; the lowest tensile results among the first five silicone RTVs tested, but very consistent | quite a bit of uncured material remaining in the center of the PVC end cap (no mm figure given) | 2 lb, quick release, not much flexibility | 42 (durometer) | lost pressure quickly at 120 PSI | FAILED, destroyed by the E10 gasoline |
| 13AC Delco$24 for 1.69 oz (spoken as '14.20 cents per ounce', unit likely should be dollars since 24/1.69=14.20) | 16.91 g | very gooey across the entire first test piece; no pound figure is given for this brand in the tensile test, only the qualitative description | not tested | did not cure and let go while still reading zero pounds, the same result as John Deere | described as a gel, too soft to test with the durometer | 600 PSI, described as a very good result despite its uncured/gel state | FAILED, totally dissolved by the E10 gasoline |
How it was tested
- tensile/pull strength test on PVC end caps, 3 samples per brand, measured in lb, after a 72 hour cure
- cure completeness at 72 hours (qualitative, plus a separate mm-based cured-area measurement given for a subset of brands: Toyota, Pro Seal, Honda Bond, John Deere)
- test cup weight of dispensed product, in grams
- durometer hardness measurement
- flex/adhesion downward force test on a plastic-to-metal bond, applied 5 inches from the metal, measured in lb until the bond released
- capstone pressure test: metal clamshell assembly pressurized with jack oil, measured in PSI until seal failure
- application-technique myth-test using John Deere as the sole test subject: skin-over wait time, surface cleaning, use of a gasket alongside the RTV, and cure time before pressurizing
- chemical resistance: 2 hour exposure to E10 gasoline, pass/fail
“The Mopar performed the best with an average finish of third place.”
Data notes and caveats
13-brand RTV gasket maker showdown (Permatex has two separate entries: Ultra Gray and Right Stuff). The video's own final scorecard gives explicit average-finish numbers only for the top 3: Mopar (winner, average finish approximately 3rd), Toyota (runner-up, 3.3), Honda Bond (third overall, 3.8); the remaining 10 brands' overall average placement is not individually stated, only their per-category results, captured in full above. Several separate category leaderboards exist alongside the single overall winner and should not be confused with it: Honda Bond won the adhesive/tensile-strength leaderboard outright (93.9 lb average); Toyota won the cure-completeness leaderboard outright (fully cured); Versachem won the flex/adhesion downward-force test outright (5.2 lb); Mopar won the capstone pressure test outright (1,010 PSI) and also had the best overall average finish. Only 3 of 13 brands survived the E10 gasoline resistance test: JB Weld, Versachem, and Mopar. Every price-per-ounce figure in this video is spoken with the word 'cents' where the arithmetic clearly implies dollars (e.g. Permatex Ultra Gray: $9 for 3.5 oz spoken as '2.57 cents per ounce' when 9/3.5=2.57); this is preserved verbatim throughout rather than silently corrected, since it is consistent enough across nearly every brand to likely be a transcription/narration habit rather than a real error, except for two flagged genuine anomalies: (1) Loctite's own stated per-ounce figure (4.33) does not match its own stated bulk price of $9 for 2.7 oz, which computes to 3.33, not 4.33 - the number 4.33 does correctly match Mopar's own bulk price ($13 for 3 oz) introduced two brands later, raising the possibility of a captioning cross-contamination between the two price mentions; and (2) Toyota's and John Deere's price-introduction clauses are spoken word-for-word identically ('$20 for three ounces or six dollars and sixty seven cents per ounce'), a likely caption duplication error, with no way to determine from the transcript alone which brand (if either) has the correct figure. Both are reported verbatim per-brand above rather than guessed at. A single-brand application-technique myth-test (skin-over wait time, surface cleaning, gasket use, cure time) is embedded partway through the video using John Deere as the test subject; those figures are kept separate from John Deere's main head-to-head results in its notes field, since they represent a different experimental question (does technique matter) rather than a brand-vs-brand comparison.