<center><img src="http://pictureposter.audiworld.com/6607/5w40.jpg"></center><p>M1 Truck &amp; SUV 5w-40! ;O)

It better be more quiet! You even got those shapely new bottles. Let me know what you observe in terms of fuel economy, power, oil temps and pressure, and oil consumption.

Is it true that when using a crude oil, such as Valvoline, and that going from that to a Synthetic, such as Valvoline, that the engine may experience damage? Or is this just a bad idea?

There is a small chance that synthetic oil will losen some sludge and clean false seals in an engine that lived on mineral oil for a very long time. If an engine is reasonably clean, there is no good reason not to switch to synthetic oil, even if the engine has over 100k miles on the clock.

PS: Valvoline makes no true synthetic oil. Their synthetics are only Group III hydrocracked mineral oils. In legalese they can call it "synthetic" -- at least in the US. Real synthetics (synthesized from for example ethylene gas) are Group IV (PAO) and V (esters). M1 5W-40 is made from Group IV and V.

i was going to get it but the truck and SUV threw me off a little. so i got 10w-30. im a little leary of the 15w-40. if its ok im going ti run the truck and SUV 5w-30 next time, see if i get any quieter, smoother etc.
thanks and sorry for the 1.8T invasion lol, i love the 12v engine i want to buy my buddys 1995 90CS quattro as a second car one day.

I went to the Audi specialist today to get my cylinders checked out. Before they read undercompression. You remember? 100-85-170. My #4 and 6 were supposedly undercompression. After they did a "leakdown" they found nothing wrong. NOTHING!! Whew!! But they told me to start switching to synthetic by usind a durablend for about 3 oil chance cycles and after that start using synthetic. They did recommend M1. Thx for the info. man. You just don't know how helpful you are. Props to you.

moribundman could probably better answer? ;O)

Calling an oil "Truck&amp;SUV" is only a marketing gimmick! What counts are the specs. M1 5W-40 is an excellent oil. I see absolutley nothing in the spec sheet that should make this oil less than very suitable for your 1.8T. It doesn't carry VW 502.00 approval, but according to the relevant specs, it exceeds the requirements for VW 502.00. If you prefer using a "proper" VW 502.00-rated oil, all VW and Audi dealers, and AutoZone carry Castrol 5W-40 for just a little under $5 a quart. M1 5W-40 is the better oil (Group IV and V), but if you prefer an oil that is VW/Audi-approved, use Castrol 5W-40 (Group III and IV).

M1 10W-30 doesn't meet the HTHS mandated by VW502.00. However, M1 10W-30 is extremely shear-stable and its slightly lower HTHS is most likely not an issue or cause for concern.

Do NOT use 15W-40 in the turbo motor. A turbo prefers thinner oil, as the turbo relies on fast flow. 5W-40 is the best all-year round viscosity in all but the most extreme climates.

If worried about your oil, have a used oil analysis performed for peace of mind and to help you figure out the proper oil change interval.

A heavy duty engine oil with dual rating for gas and diesel engines will contain a lot of detergents that may help clean the engine. Delvac 1300 S is a fine HDEO that you can safely use. It's cheap, too, especially if you buy a large container. However, it is a 15W-40, and you will lose a bit power. Gas mileage will worsen a little.

Once the engine is clean, it depends on your oil consumption whether or not you should use a full synthetic or other (mineral or hydrocracked) oil.

Oil suitable for diesel engines is generally much more robust than oil for a gasser. Cam lobe pressures and who knows what else are much more brutal in a diesel engine when compared to a gasser.

Oil for diesel motors has more anti-wear additives. As long as sulfated ash content is not beyond allowed limits (1.5% for VW 502.00), there should not be an issue with O2 sensor or cat poisoning. Oil for diesel engines also has also a superior ability to hold particles like soot and carbon in suspension, which means sludge formation is highly unlikely.

Why don't we use oils for diesl engines in gassers? Most of them are 15W-40, which means they are quite heavy and made for larger engines. A slight powerloss and loss of gas mileage can be expected. Oils that are made for only diesel engines should NEVER be used in a gasser.

Mixed-fleet (gas/diesel) engine oils are generally safe for both, diesel and gas engines. They offer the best of both worlds: they are high quality low-friction oils with a robust additive pack. That's what makes M1 5W-40 so attractive.

Mike, apart from a slightly quiter running motor, do you notice anything else? Like less power or worse gas mileage? I don't, but I used 5W-50 and 0W-40 before I switched to 5W-40.

That's a new idea to me. I don't think that they sell that stuff at Autozone.

Look for large gallon jugs. Delvac comes in black jug, Delo in a blue one. They keep those oils often around the corner and not on the main shelf. Another option is to check you local truck stop. They definitely have those two oils. Another option would be Shell Rotella T 15W-40.

If you consider the cleaning phase with mineral oil to be transistional, then my answer is yes.

If by "transition period" you mean that you go from crude to HDEO to synthetic, then my answer is no.

Your mechanic told you to start using a "durablend." That makes little sense, because a mineral/syn blend doesn't necessarily have the extra cleaning ability of an HDEO. You could also use an expensive ester oil like Red Line for cleaning, but it's a waste at $8 a quart. Best way is using an HDEO for a couple shortened oil changes (3-5k miles), followed by a hydrocracked or full synthetic oil.

If I should just use the Delvac for one oil change than after the cleaning start using Fully Synthetic M1.

Use Delvac 1300 S (or any other HDEO suitable for gas and diesel engines) for a one or two oil change intervals to clean the engine. If your oil consumption is higher than you like, I suggest you use then a good Group III oil like Castrol 5W-40, or if you have no oil consumption issues, use a full synthetic like M1 5W-40. Oil consumption with full synthetic oils tends to be a bit higher than with hydrocracked mineral oils. Due to increased slipperiness, full synthetic oil gets by the rings and valve seals more than mineral oil.

How much oil does your engine currently consume?

The Audi guy said that oil consumption is normal for this car and that a thicker oil could slow down the consumption. Did you mean a crude or syn. Castrol 5W-40 if it still eats the oil? I might still have to get the valve stem seals replaced. But with what i've heard about this engine in this forum it could be anything that causes the oil consumption. Sorry that I have to ask so many questions that need answers that any 5 year old could understand but I don't want to screw anything up. If this cars' engine does that I'm royally screwed.

Castrol 5W-40 is mostly Group III (hydrocracked mineral oil) with some Group IV (PAO full synthetic) oil. It can legally be sold as "full synthetic" in the US. In other markets it would have to be labeled as "hydrocracked" or semi-synthetic. That does not make it a bad product! As I said, if oil consumption is an issue, you may opt for using this type oil instead of a full synthetic. I think you should try it! If everything else fails, you could try Seafoam to de-carb the engine. A few guys here have been bold enough to try it, and they've reported success.




Regarding oil consumption:

High oil consumption may be common, but it's not normal. Until my A4 had over 70k miles on the clock it needed never more than 1/4 qt oil added to keep the level at max during 10k mile oil change intervals. My car developed many oil leaks, all of which make it for me now impossible to exactly say when oil consumption increased. Once I fixed my oil leaks, which happned only about 2 years ago, I figured out that oil consumption is not a bit over 0.5qt per 1k miles. I'm trying to reduce that oil consumption and am currently using DELO 400 to clean out some junk. I do know what Audi says about acceptable oil consumption, but I'm also aware they are just covering their collective, corporate ass.

Main contributers to high oil consumption:

Wear and tear:

- valve stem seals on our cars aren't very robust. if you have over 70k miles on the engine, chances are you could need new valve stem seals and that would help a lot when it comes to excessive oil consumption. It worked wonders on a VW I owned.

- sticky rings: carbon buildup in ring/groove land will prevent rings from sealing well, blowby will increase. Hence it is important to keep the engine clean by using the right oil and a proper oil change interval.

- low-tension rings: this "feature" increases fuel economy at the cost of ring life expectancy. Low-tension rings let more oil slip by then regular rings. Since ring and cylinder wear increase with age, oil consumption will increase. Again, keeping the engine clean is the best we can do.

Oil choice:

While thicker oil may help curb oil consumption somewhat, it's not a cure, but merely a baind-aid. Also, consider you do not want to go thicker than necessary, because you want oil to flow with little resistance and fast. Again, a 5W-40 is the best compromise in this regard in moderate climates.

An oil that can aid in keeping the engine clean should be used. Oil that tends to sludge (dino 5W-30) is to be avoided. Synthetic oils are preferable, but really required only if you shoot for extended drain intervals and best performance.

Driving style: Lead foot disease will increase oil consumption! Those vacuum changes that occur when stepping on it or letting off the gas will suck oil right out of your motor. Look for tell-tale puffs when accelerating or decellerating. That's mostly from leaky valve stem seals.

ill probably switch when i change my oil again, the engine is quieter with the 10-30 than the 5-30, so 5-40 should be even quieter.

I'll do the Delvac oil for one oil change to clean the engine a bit. If it still eats the Delvac than i'll go with the Castrol 5w-40 to see if it helps a bit with consumption or not. I'll be planning to replace the valve stem seals anyways. If the Castrol is still getting eaten than I'll Seafoam the engine, but that may not be necessary after the Delvac oil. Right or wrong? Should i do it now or wait untill I ran the oil that's in the engine now for what it's worth?

If you suspect the valve stem seals are shot, you should get them fixed. A leakdown test can confirm leaking valve stem seals. Blue puffs of burned oil from the tailpipe upon deceleration are also indicative of bad valve stem seals. The sooner you get it fixed, the better. Everything else regarding cleaning the engine still applies. The procedure you outlined is fine, but it may take more than one oil change interval with Delvac to do some cleaning. It is definitely the most gentle approach. If it doesn't work well enough, you can always get out the bigger guns later. ;-)

still think it's the seals? That's when they checked the compression and found no problem. Thanks for the info. You've been a huge help.