//// WARNING : Should we all be running Elephant hoses and / or Catch Cans / Oil Separators ? ////


Veteran Member
Apr 7, 2016
2003 Jetta TDI wagon, 5 sp, 226K miles
Hi All,

I was in the process of upgrading my upper and lower intercooler pipes when I determined I needed to purchase a hump hose to help fix a minor misalignment caused by my adding an upgraded SMIC. ( I have had a boost leak due to the misalignment that the factory connector hose to the intercooler from the lower intercooler pipe).

While my factory hoses / pipes have not had issue in over 435K miles , my need for the hump hose brought me to a seller of silicone hoses (which seemingly many aftermarket hoses are including the ones in Kerma's upgraded piping kit) BUT to my horror I saw in big words a warning on their site that silicone is NOT rated for contact with oil or fuel !

That got me to thinking .... how many people mod their cars and use silicone hoses without knowing that they are not good around oil and or fuel ?

I remember reading posts where blown hoses can wipe out ball bearing turbos through overspeeding should a hose blow while under high pressure.

So how worried should we be because of this ?

I am seriously thinking of running an elephant house until I can figure out a catch can / oil separator.

How about everybody else ? Is this really a big issue ? How long will silicone last when subjected to oil and oil vapor (I worry about the hump hose because it wil have a convenient "trough" to gather and hold silicone dissolving oil).

I know some silicone hoses can be made oil proof but I have not seen any reasonably priced ones advertised as such and I know the ones I am getting are not.

Anyways, any thoughts and comments are appreciated.



FWIW - The factory rubber / hoses seems great ... no issues at all for me but the upgrade may potentially have issues at some point


May 29, 2004
central Ohio
New Beetle 2003 manual
I use a way over-priced, overly knowledgeable TDI mechanic. Last car I bought was no service records, I took it to him to do TB, skid plate and all maintenance, and give it a once over. He installed a big hose from the filler cap (added a riser) down to who knows where. Guessing that's the elephant hose thingamajig. It's a big, thick thing, I doubt there's enough oil or diesel in that thing to deteriorate it. He is a firm believer in getting rid of all the re-circulated gases like what runs thru the EGR. Likes to do an EGR delete with tune, close to 2 grand. But it would be done right. If I had a newer nicer TDI I would consider it.


TDIClub Enthusiast, Principal IDParts, Vendor , w/
Aug 16, 2004
South of Boston
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
I second what Dannyboy says, Silicone is a common hose material for boost hoses. If they're multi-ply and good quality they last fine.

My tuner bugged me to get rid of my CCV routing to the air intake for years. I never did it. I've also never had a turbo fail in a lot of miles, so I'm not particularly worried about it.


Veteran Member
Apr 2, 2013
Lewisville, Texas
2001 Jetta Sedan TDI 5 Speed
And in my experience as a diesel mechanic for over 10 years, normal silicone heater hose absolutely will not stand up long term to oil. There are definitely hoses/ c.a.c. boots that will stand up to it decently, but hell, ever seen a modern diesel pickup with any amount of miles on it? Almost always see oily residue on c.a.c. piping. Why? I've always chalked it up to manufacturers using cheap hoses. I'm a firm believer in a properly sized crank case vent to atmosphere.