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View Full Version : Conventional oil to Full Synthetic Question



crazexr7
04-10-2013, 11:30 AM
Previous owner had a bottle of mobil 1 premium conventional oil in the trunk of this 1999 A4 Avant 1.8t k04, tuned.. etc.., so I'm assuming the oil change was done with conventional oil. I believe 5w30. I just bought a 5qrt Mobil 1 Full synthetic 0w40 to put in the car, and the guy at advanced auto told me I might run into problems down the road because of the conventional oil to synthetic switch. Will I be able to swap this in? Or should I do something to clean the system out before I put in the synthetic?

Any help is greatly appreciated. It's always fun having shitty previous owners [headbang]

Tanzimur
04-10-2013, 11:42 AM
The guy at advanced probably got it mixed up, you can go full synthetic from conventional no problem, but goin back to conventional then you will have some seal problems in the near future. Because what synthetic does is it kinda flares up all the seals doing a more surface area fit which is good in a way but when goin back to conventional itll shrink them one way and that's where you get leaks...

A1 A2 German
04-10-2013, 11:43 AM
Hogwash

I just made the switch from dino to synthetic 6 months ago owing the car since 2004.

I used dino for 8 years, it sounds dumb, yet really didn't care about the (a) stock motor and it's not like I'm pouting gravel in it by using dino. Zero issues with dino, and apparently, I was using the wrong oil filter too.

As I recently started putting more coin into her, and hearing I was using the wrong filter I made the switch all at once. I upgraded to the "proper" oversized Mann oil filter and went Rotella T 0w40 synthetic. Motor.............is pretty dam happy, talk about smooth.

crazexr7
04-10-2013, 12:02 PM
Ok thanks guys just wanted to make sure I don't cause any unnecessary damage or anything. It'll be really relieving having the proper oil in this engine!

redline380
04-10-2013, 12:47 PM
i dont see any issue with switch, but id stick my finger in the oil cap and feel for sludge. odds are running conventional oil in there for a long time (and lets admit if someone doesnt want to spend the extra on sythentic, they probably go 5000+ per change) will lead to sludge. if its that bad, id personally take off the valve cover and scrape the sludge off.

and ive been trying to spread this tip around. buy zip strip! it literally eats all but the thickest sludge away. its pretty cool. if the sludge is too thick to melt, all you need to do is scrape it with zip strip.

EErie B6
04-10-2013, 01:32 PM
Parts man said that cause of it being a high mileage engine. Synthetics tend to clean thing up and those things might currently be clogging leaks. Meaning little bits of sludge here and there filling gaps in gaskets and seals. Synthetic cleans them up and leaks can appear. The problem was already there before, the synthetics cleaning them up just exposes it.

People will disagree with this method, but any used engine I get, i take and do a dino oil (usually plain yellow bottle pennzoil) mixed with 1 quart of Dex/MercIII ATF. And let it run for 15-30mins gently varying the RPMs some... Then change the oil + filter again to whatever your favorite synthetic is. (Mine happens to be Rotella T6 5w-40)

I have had the oil come out anywhere from almost new looking on cars that have been well kept to black and nasty looking like it had been in there 5k. Never once had any ill effects from it. Always positive results... Smoother running, sometimes a noticible power gain, sometimes nothing detectable (on well kept motor)

This can also be done with Diesel or Kerosene... But I dont remember the exact recipe so you would have to google it. (I think its 1cup/8oz per gallon - but dont take my word for it)

schaefer921
04-10-2013, 01:37 PM
you see, you ran into this problem as soon as you walked into an advanced... and asked for his opinion.

the only thing i have ever heard about saying no you cannot use synthetic over convectional is for the application of some dodge trucks when performing an ATF flush, some do not recommend the use of synthetic because it can cause the vehicle to slip.
just sayin :)

tenspeed
04-10-2013, 01:52 PM
Will I be able to swap this in? Or should I do something to clean the system out before I put in the synthetic?

Any help is greatly appreciated. It's always fun having shitty previous owners [headbang]

The previous owner didn't do anything wrong. Yes dino oil was used but there are some people who never change oil.

Read the BITOG Motor Oil University series and you will know what is true and what is hearsay.

http://www.bobistheoilguy.com/motor-oil-101/

crazexr7
04-10-2013, 03:06 PM
Parts man said that cause of it being a high mileage engine. Synthetics tend to clean thing up and those things might currently be clogging leaks. Meaning little bits of sludge here and there filling gaps in gaskets and seals. Synthetic cleans them up and leaks can appear. The problem was already there before, the synthetics cleaning them up just exposes it.

People will disagree with this method, but any used engine I get, i take and do a dino oil (usually plain yellow bottle pennzoil) mixed with 1 quart of Dex/MercIII ATF. And let it run for 15-30mins gently varying the RPMs some... Then change the oil + filter again to whatever your favorite synthetic is. (Mine happens to be Rotella T6 5w-40)

I have had the oil come out anywhere from almost new looking on cars that have been well kept to black and nasty looking like it had been in there 5k. Never once had any ill effects from it. Always positive results... Smoother running, sometimes a noticible power gain, sometimes nothing detectable (on well kept motor)

This can also be done with Diesel or Kerosene... But I dont remember the exact recipe so you would have to google it. (I think its 1cup/8oz per gallon - but dont take my word for it)
Hmm thanks for the info, and that's exactly why he said that. I told him it had 200k on the motor and he thought sludge could be an issue if it's been running conventional for a while.


you see, you ran into this problem as soon as you walked into an advanced... and asked for his opinion.

the only thing i have ever heard about saying no you cannot use synthetic over convectional is for the application of some dodge trucks when performing an ATF flush, some do not recommend the use of synthetic because it can cause the vehicle to slip.
just sayin :)
Didn't really ask his opinion it came up in conversation. He only brought it up because I told him the previous owner put conventional in the car and it has 200k miles. He thought sludge could be an issue if worse came to worse and was just saying that it could cause problems down the road. I see that's probably not the case now

The previous owner didn't do anything wrong. Yes dino oil was used but there are some people who never change oil.

Read the BITOG Motor Oil University series and you will know what is true and what is hearsay.

http://www.bobistheoilguy.com/motor-oil-101/

I mean there are a lot of sketchy things in this car that I wouldn't doubt that it's been running it for a while. When I see a quart of conventional oil I assume the worst, on top of how the car was kept before. I just like to maintain these cars how they should be.

andyrew
04-10-2013, 03:11 PM
I switched to standard oil for one oil change (I was going to rebuild the engine soon...) and 1k miles later the oil basically drained out in 20 miles..

Still working on it...

crazexr7
04-10-2013, 05:07 PM
I switched to standard oil for one oil change (I was going to rebuild the engine soon...) and 1k miles later the oil basically drained out in 20 miles..

Still working on it...

Wait what happened? Bust an oil pan?

And just got done with the change seems to run great! That oil filter does suck though, managed to get to it and while unscrewing it oil seeped down into my hand and then I dropped it trying to get it off. Going to have to work on that, the 2.8l oil filter is so much easier! :/

andyrew
04-10-2013, 05:30 PM
Nah, all the seals seemed to just start leaking.

crazexr7
04-10-2013, 05:36 PM
Nah, all the seals seemed to just start leaking.

Hmm maybe thats why this thing leaks oil like crazy

Wraith600
04-10-2013, 07:07 PM
0w-40? Thought we should be running a 5w-40?

crazexr7
04-10-2013, 07:10 PM
0w-40? Thought we should be running a 5w-40?

It's a lot of times personal preference. I've seen a couple threads where members have said they ran 0w40 year round and have had an overall good experience. I could not find 5w40 around me at all so I had to settle for a $37 5 quart 0w40.

crazexr7
04-10-2013, 07:18 PM
i dont see any issue with switch, but id stick my finger in the oil cap and feel for sludge. odds are running conventional oil in there for a long time (and lets admit if someone doesnt want to spend the extra on sythentic, they probably go 5000+ per change) will lead to sludge. if its that bad, id personally take off the valve cover and scrape the sludge off.

and ive been trying to spread this tip around. buy zip strip! it literally eats all but the thickest sludge away. its pretty cool. if the sludge is too thick to melt, all you need to do is scrape it with zip strip.

Where can I find this zip strip?

redline380
04-10-2013, 07:39 PM
Where can I find this zip strip?

at any hardware store or paint selling place. It is meant to strip paint away. When I was building my junkyard engine, I got tired of scraping all the dry sludge out of the VC and oil pan. You'll never get it perfect that way. So I just started using different chemicals. Turns out zip strip is the shit when it comes to melting sludge. Just don't put it in you engine while running lol

crazexr7
04-10-2013, 07:43 PM
at any hardware store or paint selling place. It is meant to strip paint away. When I was building my junkyard engine, I got tired of scraping all the dry sludge out of the VC and oil pan. You'll never get it perfect that way. So I just started using different chemicals. Turns out zip strip is the shit when it comes to melting sludge. Just don't put it in you engine while running lol

Oh cool thanks for the heads up! I'll have to remember this if I have to do the valve cover gasket at any time.

98A4TurboAWD
04-11-2013, 06:40 AM
In my experience, synthetic is not a necessity. I have used and have seen many reputable people use and recommend quality conventional oil so long as it's changed at the proper interval. Change it every 3k and you will be just fine.

I run fully synthetic motor oil because I don't like changing my oil every 3k and with the price of synthetic being on sale at advance, I can get it for not much more than conventional, and I can run this oil for 6-7k and not worry about it.

Synthetic has been shown to go way above and beyond the 3k interval. I have seen upwards of 10k miles in some tests but I don't feel like digging them up at the moment.