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Please Help...Oil Question....Confused

968 Views 11 Replies 7 Participants Last post by  vuvision
Ok...Long story short...Bought car with 88k miles..Changed oil at 89200 miles with 5w40 valvoline synpower and A premium wix filter and had very loud engine tapping while start up and when real hot out..After 300 miles I replaced oil with conventional 10w30 and a genuine vw filter..Appeared to quiet down a bit on start up but seems to be a bit louder now and you can hear a tapping (top end?) when its real hot out...Car never had synthetic before i did it a couple of weeks ago.The vehicle now has 90700 miles and I just want an oil that will not make me paranoid.Any suggestions would be helpful.All I know is that this thing was as quiet as can be before i changed the oil and now its not the same..I guess long story not short.
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Oh yeah...Car is a 98 1.8T...Should I use Castrol 5w50?
well sorry to not have an answer as to the knocking, but I did find a *very*good write up on oil and synthetic vs regular, its got some fluff but the guy seems to really know his stuff, real meat starts @ page 25 or so, I have been contemplating switching over also, I have a '01 V6 GLX w/95k.

Definitely use synthetics in your engine as told so thoroughly in the document in this link, VERY VERY interesting reading. The guy is a dealer for AMSOIL products so maybe take the plugs for their stuff with a grain of salt but the technical information is SO thorough. The meat of the “eBook” starts on page 25. I have attached the latest testing results ranking oils based on many factors from him.


One way to ease your paranoia may be to have an oil sample tested...

I'm thinking of trying them, too (coming up on 75K, running M1 0w40 since 55k, and wondering how its doing). They're recommended by


Is there any hard evidence of a corellation between lack of valvetrain noise and proper lubrication? ...or does is just seem like there "should be"?
The Full Syntec would be a great bonus to the car, it would not have anything to do with the knocking sounds that you hear, you need to have it checked to make sure of what's going on. Good luck and STAY with full Syntec IMO :thumbup:
I am not an oil expert. I have read many posts on this site concerning oil. The following is a short compilation of my readings. The 1.8T is very susceptible to oil sludge build up, especially the 98-99’s. Posts on this site have stated that synthetic oils contain more/stronger detergents. Your engine may be experiencing sludge build-up. The synthetic’s detergents may have knocked loose some sludge particles, which are now the genesis of the noise.

There are many people on this site that swear by a product called Auto Rx; it is an oil detergent that is suppose to clear out oil sludge slowly (preventing the clogging of your oil pump and screen => engine death). The makers, and users, claim that after using auto Rx engines have run cooler (since the sludge is gone) and quieter. I would recommend running a search on this site and read our member’s remarks. One of the posts actually has the link to auto_rx.

I switched to Mobil 1 synthetic at about 24K. I have run Mobil 1 5W30, 10W30 and 15-40W, all without abnormal noise or heat. I now have ~65,000 miles on my B5. During my next oil change, I will be using a WIX brand oil filter, which adds about .5 qt oil capacity to our pitiful overall capacity, and possibly auto-rx (I have a ’99).

Here is another oil expert page: … may be worth your time. I believe that they host an article on auto-rx as well.

You could send off an oil sample for analysis. There are posts on oil analysis services on the site as well. If you are confident that your problems stem from the oil change, it may be worth the ~$30.00, plus the two oil change costs, to run a bottle of auto-Rx through your engine and rule out the sludging issue.

Good luck and let us know how it works out.
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Thanks for your feedback...I think you are correct in the fact that the synthetic oil cleaned some of the sludge out and now I have that noise...My question is that I would like to know how to possibly eliminate the tapping noise that I am now experiencing.Should I do the auto rx thing and hope that It doesnt get worse in the meen time or should I maybe try a thicker grade oil?Maybey a synthetic blend castrol 10/40 where maybe the blend will not be such a detergent?
If you believe the problem resulted from the oil change, I would read the threads concerning 1.8T sludging and auto_rx. This will help you understand the process you are about to perform, and provide you insight concerning what other B5er’s have experienced. If your B5 is not chipped, I would run the owners manual recommended weight oil for your temperature range. I believe that the auto-rx procedure recommends regular dino oil, no blends or synthetics.

Bottom line: If sludging is the source of the problem, you want/need to clean this out as soon as possible. The cleaning procedure should resolve the tapping. Changing the oil weight may only mask the source of the problem. I would switch over to synthetic after you complete the cleaning procedure. Synthetics are not a cure for all oil related issues, but from what I have read, they reduce many of the oil related problems associated with our engine.

Worst case: you are “out” the cost of two bottles of auto_rx and two oil changes (with the mileage on your B5, auto_rx recommends two bottles, read the procedure) and you have a clean engine. Best case: you resolve the problem for roughly the cost of one labor rate hour for a dealer mechanic.

Note: my comments assume you are currently using the owner’s manual recommended weight oil for your local temperature/driving conditions.
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I would also perform a search on member "ericpeterman". He has a few very informative posts on the subject; appears to be the forum expert concerning sludging.
I am running mobil conventional 10w30 right now just because I removed that synthetic that was in there when this all started to happen..The 10w30 has about 1000 miles on it right now.I think I will order the rx and see what happens.My owners manual says that I can use anything from 5/30 to 20/50 depending on the temp.Its been about 90-95 degrees here in boston the past few days so maybe I should go with a higher grade when I get the RX...
soundfxinc: I also answered your other thread. Sorry you're having this problem. I really sympathize. The good news is that it is resolvable and you'll end up with a great engine, the bad news is that you may or may not have "time" to de-sludge before the problem becomes so acute that you HAVE to remove the oil pan (not easy at all) to replace the oil pump or clean the oil intake screen. Hopefully you can nurse it along enough (run it to the point that the oil light comes on, then let it cool again, repeat) that the Auto-RX can do it's thing to clean up the sludge.

To put off the onset of the oil warning while you're Auto-RXing I'm not sure whether a lighter or heavier oil would be best. Lighter will slip by the clogged intake screen more easily, heavier attains pressure better. Hmmmm. The fact that it happens after the oil warms up tells me you may be better with the heavier oil. The main thing: don't let it run once the light comes on. Let the oil cool again otherwise you'll be buying a turbo.

Keep us posted on your progress.
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atomicalex said:
Synthetic oil will not leak out. We are long past the days of pure PAO oils.

If you have a high mileage V6, I would consider a 10W40 synthetic product.
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