# Do extended oil change intervals cause seals to fail sooner? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [February 21, 2024, 4:13pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406 "2024-02-21T16:13:16Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![TheWonderful90s](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/thewonderful90s/32/29584_2.png) [@TheWonderful90s](https://community.cartalk.com/u/TheWonderful90s)\ **Post date:** [February 21, 2024, 4:13pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406/1 "2024-02-21T16:13:16Z")
Was replacing seals on a 1992 Toyota. The oil pump seal had failed. The was rubber is all hard. A noticable groove was worn in to the shaft. The thing is the non engine oil seals seem to last longer, like the transmission and power steering pump seals. The valve cover gasket was hard at room temperature. I heated it up like it would be on the engine and it became flexible, but only on the outside where there is no oil exposure. The inside stayed harder and it actually cracked when I flexed it. The whole thing is about 6mm wide and the 3mm on the inside cracked. Something in the engine oil must degrade the rubber. This car got synthetic oil changes about around 5k to 6k miles over the last 20 years. So when we have these 10k+ mile oil changes, if the engine doesn’t wear out, will oil seals fail sooner than with traditional 3k mile oil changes? Because the contamination of the oil would be the same whether or not long life synthetic oil was used. I was thinking maybe that’s what causes the seals to degrade, and not the oil itself. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [February 21, 2024, 4:15pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406/2 "2024-02-21T16:15:48Z")
The seals harden from heat and age, not from the contaminants in the oil. So I very much doubt they’d be affected by the oil change interval. The only thing that would change that is the use of ‘high mile’ oils, ones that include additives to soften seals and gaskets to reduce leakage. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [February 21, 2024, 9:48pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406/3 "2024-02-21T21:48:26Z")
Good question. Hopefully some inde-organization will do a scientific A/B study, comparing similar cars used in a similar fashion, but with differening oil change intervals. Maybe such a study has already been done? ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [February 21, 2024, 9:50pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406/4 "2024-02-21T21:50:20Z")
Nobody’s going to spend time looking for the impact of OCI on gasket leak frequency, because there’s no obvious reason they’d be related. ---
**Author:** ![PvtPublic](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/pvtpublic/32/13089_2.png) [@PvtPublic](https://community.cartalk.com/u/PvtPublic)\ **Post date:** [February 21, 2024, 10:53pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406/5 "2024-02-21T22:53:09Z")
> [@TheWonderful90s](#): > > Was replacing seals on a 1992 Toyota. The oil pump seal had failed. The was rubber is all hard. > [@TheWonderful90s](#): > > The valve cover gasket was hard at room temperature. And this was surprising on a 30 year old car.? Sounds normal to me. ---
**Author:** ![LoudThunder](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/loudthunder/32/27769_2.png) [@LoudThunder](https://community.cartalk.com/u/LoudThunder)\ **Post date:** [February 22, 2024, 3:41pm UTC](https://community.cartalk.com/t/do-extended-oil-change-intervals-cause-seals-to-fail-sooner/194406/6 "2024-02-22T15:41:12Z")
I have often performed maintenance on engines where the valve cover and/or the oil pan gasket was as hard as a rock and actually broke apart as it was removed, but there were no leaks from those old, dried hard gaskets… Just so you know… Sure, it they shrink as they age, leaks can occur, but not necessarily…