B7 Oil Consumption Issue

B6/7 S4/RS4
#1

Hey All,

Happy to be a Newbie here. Have an '06 Silver B7 S4 6spdMT with close to 90k on her. Running a full miltek non-res exhaust dp’s and all and love the car. However, Im not mentally prepared to continue to replace 2 quarts of missing oil every time I drive the poor thing 1000 miles, it kills me. FYI Ive had NO other problems (knock on wood) with the car and she absolutely runs like a train. Been running Mobil1 5w40 since ownership 2 years ago but plan to switch to LubroMoly 5w40 before the snow tires go on. After a bit of research Ive been frightened in to changing my PCV (next week) and now am learning of possible scored cylinder walls. WTF?!?! I was recently told that it could be an issue with the pre cats on my miltek exhaust. Does anyone have any experience with this issue? Is there any way to gut the precats out of these downpipes? If I went to catless dp’s what are the odds Id pass emissions in chicago and would this make a difference in terms of oil consumption? Is there anything Im missing? Any and all help is greatly appreciated! Thanks in advance to all.

#2

Welcome to AR! Lots of informative people here on this site.

The Oil consumption seems to be a common issue with the audis and more so with the S4/RS4 cars from what i’ve learned ( correct me if im wrong ). The PCV seems to build up with gunk over time and should be either checked and cleaned, and/or replaced. Those are one of the issues but im sure someone else will chime in on that to further help with your issue.

“Piggy Pipes”. Gutting the precats on a B6 S4 is not too hard of a task to do yourself, if you have the right tools and some mechanical know how. You can still pass smog with them out but check your state laws before doing so.

Full race downpipes will not pass the “sniffer” at the smog shops. You’ll need at least some race cats to help burn up that extra bit that doesnt get burned from the engine.

Hope this helps.

#3

kirillo23 welcom.

Oil consumption on the B6/7 S4 seems to be a little more comon then with other motors that Audi has. I will tell you that the aluminum blocks that are the main stay of the 4.2 now. Don’t react well to the precats. S5’s are not known for burning oil as much or at all. I did notice that when I removed my Precats reciently (its a large PITA on a S5) that the car ran better and it seems that the oil consumption has gone down a bit if not completly non existent.

Two quorts tho seems like quite a bit. Where in chicago are you? I would see if you can get a local guy to help you do a compression test. This will help let you know if your looking at scored walls or maybe even a valve guide issue.

My thoughts are this. If the car isn’t smoking thats a good thing but you have precats in so this would mask that.

Regardless of your next move removing the precats would be first on my list.

#4

glad to see you made it.

I think your on track with the usual suspects. Start with the PCV and Pre cats if you can. Asses what the results were and then go from there.

Ill bow out for a little while and let the experts chime in.

#5

From what I have seen in the past, hope it’s the PCV. It could be the pre-cats but 2 Qts does seem like a lot for 1k miles of driving.

I wouldn’t say it’s common, but it does happen often enough. Personally I think it has to do more with how the car is driven after startup. I think waiting until the motor is properly warmed up before going hard on it as well as routine maintenance are key factors. The original owner of my car rarely drove the car, and maintained it meticulously. I have had it for 3 and a half years, done all the routine maintenance, I drive everyday and have always waited for the car to warm up properly before ever getting on it.

My car is now around 61k miles, and doesn’t burn any oil. My car has an 11/03 build date, but the biggest issue my car has had was a window regulator. You will hear about issues more than you will hear “Everything is ok” but it doesn’t mean it happens often. All it means is some people are more vocal than others.

As for going catless, it all depends on if they are using a sniffer test at the facility and if you have a tune as most places just scan for codes. Will it solve your oil consumption issues, probably not but it will sound and run a lot better.

#6

I might have some experence in this field as I worked for the borla corp for over 10years.

From an exhaust stand point the Pre Cats indirectly could be part of your issue. The Pre Cats hold too much heat, this heat backs up into the cylinders when flow pass threw isn’t enough. Pre cats are the death of most domestic motors as well. In the domestic motors it comes in the form of leaky valve seals.

At this point if your buring that much oil. The Pre Cats might have already done damage. Removing them will help cut down on the issue but how much is unknown.

There is a good chance its a collection of

The oil your using
The Pre Cats
The warm up time before you drive
as well as the PCV system

The Milltek Cats are super prone to fail so I would remove the Pre Cats and if you really need to keep the cats get a proper set of Dp’s and just use piggies.

#7

Cannot thank you guys enough for all the great info, like I said before its great to be part of a forum where people actually care to help you out. PCV replacement next week and pre cat gutting as well will occur. Ill have to put close to 1000 miles on her before I can tell for sure exactly how the oil consumption has been effected. What is an honest and reasonable price to get the pre cats gutted? Just want to make sure i dont get ripped. I know it cant be much more than a 2 hour job.

As far as running her hard while cold, its one of the biggest no nos you can ever do to a car. I ALWAYS let her properly warm up before going anywhere over 2500 rpms and Im a tad insane about the upkeep on the car as well. Unfortunately, I bought the car at 48k miles and have no clue how the previous owners treated the car.

Thanks again you guys, will re post after the repairs and see how she is.

#8

Another quick question:

Is there any way to tell if cylinder scoring is present without cracking apart the motor?

#9

you can do a compression test or a leak-down test. This will help show the amount of leakage that is taking place on each cylinder. Its very valuable. Its a great way to tell you the health of the motor. Doing this will provide you with one step in the many to see what kind of condition your motor is in.

The PreCat is a serious performance killer as well as a component that can and will do damage to your motor if left unchecked.

#10

JHM offers the service to do the piggy pipe modification. includes gutting the cat and re-locating the o2 sensor to avoid codes.

Heres a link to there site with the service.
http://jhmotorsports.com/shop/catalog/exhaust-downpipes-jhm-b6b7-s4-piggies-p-395.html?osCsid=3a0b3e778b1e0cd457a95f7ab1f428fc

#11

I know Im late to the party and a lot smarter people then me have posted but. From my experence most cars have had issues with the precats. The B5 S4s used to blow the turbo seals out after not too long if they kept the Precats in and started looking for more power.

#12

For perspective, if you were under warranty and did an oil consumption test with Audi, they would consider your oil consumption excessive and would then investigate deeper. I believe their threshold is one quart consumed in about 700 miles (or 1100 kms).

This generally turns into a new longblock or shortblock as they seem pretty content to call it a compression issue caused by cylinder wall damage, and throw in a new motor. Seems a bit excessive…I imagine if you looked at any 4.2 there would be some cylinder wall damage, so I’m not satisfied that the new engine is the best ‘solution’…it’s just the most readily apparent/easiest to blame cause. I bet tons of these engines that get pitched had something more simple wrong with them…and I bet that many of the problem free engines have visually apparent scoring that a tech would point to as a reason for a new engine.

In any event, cross your fingers on the PCV. That would be a bonus, as its a cheap and easy fix. Hopefully JHM addresses refurbing this and gives us another option.

#13

I fully agree. Are you able to do a compression test. This would really help move things along information wise.

#14

Today is the big day. The pre cats are getting gutted, PCV is getting replaced, and lubro moly 5w40 is going in her for the upcoming winter all in just a few hours here. Trust me, my fingers are very crossed. I can have my mechanic do a compression test while im there today but if the car pulls like a train still, doesn’t that mean my compression must be pretty good? Im going to ask about a leakdown test when I get there, hopefully 1 of the 2 tests if not both will help indicate the condition of the motor itself.

Ill be sure to log the dates and mileages in order to keep a super close eye on the oil issue and see if any of this helps. Ill repost my findings. Thanks again to all of you guys, huge help.

SK

#15

Deff if he can do a compression test that would help let you know if you need a leak down test.

Sounds like your on the right path as far as getting the stuff done to cut down on or eliminate oil consumption.

#16

you can get a compression tester at sears, ive had mine for years. while you are doing that, if your plugs are over 10k miles, might as well replace them too, good way to bring back some lost hp. best of luck to you. how many miles on the car?

#17

Here is what they’ve told me about my flashpoint downpipes…

“A couple things- The Flashpoint downpipes utilize a single pair of high flow cats, in the location of the stock precats. The reason you see downpipes with cats here, versus down below where the OEM main cats are located, is due to the heating of the catalyst itself. Having the only cats located farther downstream will guarantee a check light nearly every time the car is started. This is the reason the cats are up top.”

Being as I need to pass emissions, I obviously cant gut the main cats, and they’re telling me that there are no pre cats on these downpipes. Will this particular positioning of the main cats, (where the oem pre cats are normally located) cause the same problem that the oem pre cats cause? I don’t give a hoot about my light coming on and never have, I wish I knew all this before I bought these dp’s. What should I do? Sell the downpipes and get another ser? Annoyed, frustrated, and needing suggestions. Thanks

#18

I’ll let others bash the response you received in more depth. ;D The short version is they are idiots. You can avoid the catalyst efficiency error code a number of different ways. The reason they gave you for their cat location is lame. It tells me they don’t fully understand the basics of performance or longevity amongst other things.

The location of the pre-cats (or any cats located that close to the motor) is the issue. As others have said they hold heat…a LOT of heat, increasing cylinder temps etc. It also impedes exhaust flow being that close to the manifold etc. All bad things you can avoid by doing piggies or buying a proper aftermarket set of DPs.

Long story short, the ideal location for cats (any cats, preferably hi-flow) is as far down the DP as possible - away from the engine. This helps keep the heat further away from the motor and improves exhaust flow.

You can pass emissions as long as you can pass the readiness test (not sure where you live but that is how it works where I do and some other states). This can be accomplished via a tune or 02 spacers.

So you have some options available to you. My suggestion, dump the current DP’s and get a new set from JHM. Or source a cheap set of OEM DP’s from somewhere and gut the pre-cats.

#19

The above post sums up everything I was going to say.

The PreCat Dp’s are junk. Flashpoint downpipes are just cheep china made Dp’s including the precats. In the future feel free to come here and ask all the members what they think. I also suggest you recommend others to do the same as well.

To be honest your better off selling the flashpoint junk and getting either completely catless dp’s or a set of stockers and doing the modification.

Short and sweet. dump what you have there actually in some ways worse then the stock dps you had on the car. “high flow” cats is just a term for junk cats that don’t do there job even worse they actually end up flowing less then the stock cats they replaced…

I will make a post sometime soon about my experience at borla and what Ive learned about some of these so called exhaust manufactures and there “Cats”

#20

So let me get this right before i fu** up again.

I would be better off selling the flashpoint dp’s and buying a set of piggie (oem w pre cat gutted) from jhm and replacing? I dont even care about performance, I want the motor to stay as healthy as possible here.

How much do I even ask for these things and where do I even sell them? How lame

Thanks again guys.