Cal Club Autocross Forums

Hey guys

Yesterday I changed the oil on my Audi (3.0 30V 6 cylinder) and at the last minute (1 a.m. in the morning) I realized that I got the wrong oil (5 quart 10w30 Mobil 1 synthetic) instead of 5w30. So I ended up using
5Q 10w30 and
1.8Q 5w30

Instead of 6.8Q of 5w30 or 5w40 that Audi is recommending... is that a really bad thing?

EDIT: The engine has 70K miles but it doesn't burn oil

OMG it's going to explode............................

Not.

You'll be fine just go back to your usual oil next oil change.


http://www.nordicgroup.us/oil.htm

lot's of good info

Tom Denham wrote:OMG it's going to explode............................

Not.

You'll be fine just go back to your usual oil next oil change.


http://www.nordicgroup.us/oil.htm

lot's of good info

Thanks, so I guess not need to continue carrying the fire exstiguser with me all the time
Good info on that link!

Sometimes car companies recommend using thinner oil to get every so slightly better fuel mileage ... for their "fleet" averages. Especially with a mature car with miles on it, going to a 10 weight oil is no big deal!

Subaru recommends 5 weight oil in general ... THE Subaru of America mechanic that takes care of the HQ's Subies (like their super rare in house 22B) uses 10/30 dino oil instead of the recommended 5/30 lube.

Mako Koiwai wrote:Sometimes car companies recommend using thinner oil to get every so slightly better fuel mileage ... for their "fleet" averages. Especially with a mature car with miles on it, going to a 10 weight oil is no big deal!

Subaru recommends 5 weight oil in general ... THE Subaru of America mechanic that takes care of the HQ's Subies (like their super rare in house 22B) uses 10/30 dino oil instead of the recommended 5/30 lube.

Thanks Mako, I feel a better after reading your message

As long as you have been using the correct VAG-spec oil (502.00) up until now, I wouldn't worry about it. At that mileage, One oil change shouldn't hurt.

Here is the 411 on what the numbers mean on multi-viscosity oils.

The first number ( 5W ) is the oils' viscosity when "cold". The second number ( 30 )is the oils' viscosity when at operating temperature.

It just allows for a thinner oil during start-up which means less wear.

On the other hand, the greater the range, the faster and easier the oil will break down since it has more polymers in it. So that just means more oil changes.

It just allows for a thinner oil during start-up which means less wear.

Hardly a factor in our climate. One could make a point that the slightly thicker oil leaves more of a coating between starts = less wear at start up.

Mako Koiwai wrote:

It just allows for a thinner oil during start-up which means less wear.

Hardly a factor in our climate. One could make a point that the slightly thicker oil leaves more of a coating between starts = less wear at start up.

That's a false assumption. Bearing lubrication is all about oil flow through the bearing. A thicker (more viscous) oil at startup is not going to flow as much, so more wear will occur.

Hardly an issue in Southern CA. Yes, if I was taking my race car into the mountains I would worry. Off the top of my head, I believe 10 weight is OK down to freezing, 5W below freezing.

Thanks Tom

Mako Koiwai wrote:Hardly an issue in Southern CA. Yes, if I was taking my race car into the mountains I would worry. Off the top of my head, I believe 10 weight is OK down to freezing, 5W below freezing.

Those charts aren't necessarily accurate. Bearing clearances, pump characteristics, passages, etc all play a role in oil flow across the bearings.

If it's good enough for the head Suby mechanic at Subaru of America's headquarters, in New Jersey, it's good enough for me. See how cold it is over there right now! 5/30 is a relatively new development ... but you're correct that modern cars have higher tolerances. But it's my understanding that the car companies went to 5/30 because they were trying to eek out every last bit of mileage. 5/30 oils go through our older engines, my Previa and the Miata like water.

I wonder about that chart too.

If the 5w-30 operating temp is only good up to `95 deg. F it would be logical that a lower weight would be even lower.

So what exactly is the operating temp range of the 0w-20 the '07'-'10 Tundras call for? Can imagine it would fall lower... as we've run the trucks hard on Dyno's for 4+ days straight in 100+ degree temps whale on programs in '07 & '08.

Webster Jessup wrote:

Mako Koiwai wrote:Hardly an issue in Southern CA. Yes, if I was taking my race car into the mountains I would worry. Off the top of my head, I believe 10 weight is OK down to freezing, 5W below freezing.

Those charts aren't necessarily accurate. Bearing clearances, pump characteristics, passages, etc all play a role in oil flow across the bearings.

Basic Guidelines for the uninformed, not the holy bible

What do you thing about using 0/20 weight racing oil ... for a AX only car ... for the ultimate in low friction. Only good for 500 miles between oil changes!

http://www.silkolenestore.com/more.asp?ProdID=142

What do you thing about using 0/20 weight racing oil ...

All the theory is great. But what is happening in your engine when you are focused in that comptitive haze, your gas pedal is on the floor, you are pulling max g's in the corner at 6000 rpm and most of the oil is up in the valve gear or slung to the side or the oil pan away from the oil pickup? Do you want the lightest weight oil or the one that gets you the best mileage? Are you concerned about the car manufacturers meeting their CAFE mileage numbers? Or do you want the one that may be slightly thicker but gives you better rod and main bearing protection during the momentary loss of oil pressure?

In So Cal you are more likely to see higher temperatures where you would want the thicker oil. Unless you plan on racing in Big Bear in the middle of the night in the snow, I wouldn't worry about the better cold start characteristics of the ligher oil.

And yes, I would use Red Line in it in any case, but that's me.

John Fendel wrote:
And yes, I would use Red Line in it in any case, but that's me.

Look how long John's car has lasted!

I agree ... just posting that as 1 step further down the line from 5w30. But it is a PURE RACING oil ... interesting that it can be that thin yet engineered to keep a strong enough film between high pressure areas.

I agree ... just posting that as 1 step further down the line from 5w30. But it is a PURE RACING oil ... interesting that it can be that thin yet engineered to keep a strong enough film between high pressure areas.

In The Red Line racing oil, the lubricating properties are actually better then the street oil because they don't add as much detergent package. The detergents actually reduce the lubricating properties, but are necessary to keep the engine internals clean during extended drain intervals. The assumption with the race oil is that you will change it much more frequently i.e. after every race or so, thereby draining out any deposits before they can collect in the engine. I wouldn't use a race oil in a daily driven car.