IPD has 3 oil filler cap seals - a $0.65 aftermarket one, a $6.95 IPD one and a $8.59 Volvo one. Is there any real world difference in longevity? I'm happy to spend a few dollars if it means I won't have to mess with it for a while but if I can save $8 without impacting performance, I would prefer it.

What model and year is your car.

Is the seal hard and inflexible?

If it still flexible and your car is old, the cap may be loose - You can bend the fingers a teeny bit to make it seal better

I agree that the oil cap seal is a cheap part and worth just replacing. If you don't have time to order one and just want to move forward, you can also just cut a gasket the same size and add it behind the original so it's tight again to stop the leak. You can always wait and order that after when it's convenient for you.

Most O rings are Neoprene, I think its more resistant to oil than natural rubber like from rubber trees. Natural rubber has some certain properties, for example it is used on pool tables where the bounce is important and it has a more grippy texture so that can help if it's a roller used to drive things like paper.

There are a bunch of different synthetic compounds. Butyl rubber is one. Natural rubber has a shelf life , eventually it goes hard and breaks down. Its probably less oil resistant than most of the synthetic rubber products of today.

the natural rubber needs a different process, some of the synthetic rubbers are easily molded and cured hard with heat. I worked at a place that made printing press rollers, it came in drums and we put it in molds , cured it in an oven than ground it to final dimension.

here's a pretty informative short video that shows natural rubber being made and extruded for pool table cushions at the Brunswick factory.

https://www.youtube.com/watch?v=qyiDDhNaczw&ab_channel=kdmunroe

Aftermarket oil filler cap rubber gaskets from reputable manufacturers like Reinz and Elring are typically under $1 and perfectly decent in my experience. Reinz is a well known supplier to Volvo. At that price I usually buy a few at a time. They only take a moment to change as soon as the old one starts to become hard and brittle.

Probably not a bad idea to order one or two cheap copper washers for the oil pan drain plug at the same time under the same shipping charge. After a couple of uses they also become hard and prone to weep. Or you can reuse them, using heat to anneal and soften the copper occasionally.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thanks for the info. I always keep a few washers around. Cheap enough that I use a fresh one every time. Probably overkill, but a few cents is worth keeping oil spots off the driveway.

Hi,

I agree with Dave whole heartedly.

The price spreads between those examples is a reason not to other business with the other parts offered.

I found the following by using randomness of a search engine and selecting out what I know about rubbers.

https://www.rubbercal.com/sheet-rubber/synthetic-rubber/

This site puts in the effort to tell us that after the natural tree rubber everything else is synthetic.
Synthetic means manipulating to made for certain qualities.
I skipped around to find some on rather repetitive but I got a better explanation as it went along.
Neoprene and Nitrile are closely the same so it explains the “ripping off” marketing does within price ranges.

If you look at the prices and amounts of products offered in the explanations on this website you can get the best view of what a rip off that price spread is.
The sheets are three by six feet. That’s a lot oil cap gaskets that IPD can have made to sell as aftermarket.
Imagine E EURO and FPC are doing the same thing. I think I got mine from them as they do work to get our business too.

There isn’t that much difference as long as you stay above the generic EDPM that’s a catch-all synthetic rubber. I gathered that’s it’s just above the natural tree rubber limits many years ago.

Thermoplastic and urethanes are the latest upgrades in the industry and their pricing has improved a lot.
So shop around for any of these technologies and weigh them accordingly.
Manufacturers all do it, we just to sort out the greedy ones!


Phil

I appreciate the info. Thank you.