Randolph

I've been running 10W-40 castrol full synthetic year round with no problems. I noticed that Castrol offers 5W-50 full synthetic. I don't recall ever seeing this type of viscosity. I wonder if this would be better than what I'm currently using? I know some on here switch oils depending on the season but I'm not interested in doing that as I'm not always due for an oil change when the season is changing and to me that is a hassle. Any thoughts on this 5W-50 weight? I like the idea of having 5 weight in the chicago winters and the 50 for the really hot summers but again I've had no problems with the 10-40 either. I'd hate to kick a sleeping dog by switching it but if it keeps the dog sleeping even more sound than why not. I'm not a nutjob on oil weights nor am I trying to start a long thread on a very beat subject but some of your opinions on this would be would be great. We talking for an 87 5KCSTQ. TIA

R

MrGoodbytes

You can change if you want. It'll provide better protection on first cold starts and at hotter temp

ekellock

Then there's always the issue of the extra additives required to give it that wide a range.

MrGoodbytes

That was my original concern, but I think they've gotten that under control.

Randolph

I may switch over to see. Every once in a while I'll get the "lifter tap" but it's very random and seldom happens, maybe 5 times a year if that. When it does occur it lasts for about 2 seconds. My mechanic said that's fine and not to worry about it. I think my biggest concern is if those lifters will not like the lighter 5 weight. Hmmm

R

MrGoodbytes

There seems to be a gross misunderstanding of what the oil numbers mean in the automotive world. I see it every day.

The W doesn't mean weight.

5W50 is not a "5 weight oil."

The numbers are pretty much arbritrary and only there for comparison's sake.

The first number is the "weight" of the oil at cold temperatures. The second number is the "weight" of the oil at hot temperatures.

The oil isn't always 5. It's 5 around 5ºF or so. At really cold temps. Most of the time, it'll probably be around 20-30 weight.

Here's a really basic chart:

<img src="http://www.aa1car.com/library/oil_chart.jpg">

The 0W30 has the same basic protection range as the 5W30, but since it has better viscosity management at colder temps, it gets a 0 instead of a 5.

All the xW30's will have the same upper limit of viscosity rating. They will be inherently thinner than xW40's, which are inherently thinner than xW50's.

A 0W30 and 0W40 will act almost the same way until they reach very high temps (50-60ºC). In which case the 0W40 will be thicker.

Thicker doesn't always mean better, though.

The difference between a 10W30 and a 0W40 will only be apparent at very cold temperature and at very high temperatures (where the 0W40 will maintain "normal viscosity" better).

0W40 will act like: 0W30 + 5W20 + 5W30 + 10W30 + 10W40 + 15W40

5W50 will act like: 5W20 + 5W30 + 10W30 + 10W40 + 15W40 + 20W50

Having the right viscosity for the right environment is what's important. What's nice about 0W40 (Mobil's oil) and 5W50 (Castrol's oil) is that they account for almost any temperature environment and thus are great.

That's all I have to say about that.

Audi Junkie

That system is long gone, although people still grapple with understanding the system in those terms. Nowadays a 10w is tested at -20f, a 5w at -25f and a 0w at -30f.

Audi Junkie

5w-40 is the classic Euro visc range and what is specified by specs like VW 502. Syntec is generally just ok, unless you are talking about the imported German Syntec. In your car, I'd consider HD diesel 5w-40s like the (new) Mobil 1 Turbo Diesel Truck 5w-40 or Shell Rotella T Synth. Check out WalMart truck oil section. 2 other oils would be Mobil 1 Hi-Miles 10w-30 ( a heavy 30) or MaxLife Synth, which comes in 10w and 5w-30. The heavy Euro 30s will offer good mpg.

fwiw, here is a pic from inside a Audi 12v after 122k of 10k intervals on Syntec 5w-50.

<a href="http://s15.photobucket.com/albums/a364/AudiJunkie/bitog/?action=view&current=122k_miles.jpg" target="_blank"><img src="http://i15.photobucket.com/albums/a364/AudiJunkie/bitog/122k_miles.jpg" border="0" alt="Photobucket"></a>

German Syntec, one of the few 30 weights that make Euro specs...

<a href="http://s15.photobucket.com/albums/a364/AudiJunkie/bitog/?action=view&current=gclabel.jpg" target="_blank"><img src="http://i15.photobucket.com/albums/a364/AudiJunkie/bitog/gclabel.jpg" border="0" alt="Photobucket"></a>

MrGoodbytes

My company recently started carrying Mobil 1 0W20 and clearenced out their 0W30 (AT $2/qt!!!!!!).

I'm seriously considered switching to Mobil's diesel 5W40 next change.


" A 0W oil is tested at -35°C, a 5W at -30°C and a 10W is tested at -25°C. The real-world ability of an oil to crank in the cold is diminished soon after put into service. The motor oil grade and viscosity to be used in a given vehicle is specified by the manufacturer of the vehicle (although some modern European cars now make no viscosity requirement), but can vary from country to country when climatic or mpg constraints come into play. Oil circulates through the piston oil rings to cool and lubricate the compression rings. Inside gasoline engines, the top compression ring is exposed to temperatures as high as 320 °F (160 °C).

Many new vehicles are marked to use 5W-20 oil (Honda, Ford, and more recently Toyota) which is not much thinner than a 30 weight oil. Nay-sayers of 20 weight oil's ability to protect engines should note that typically, 30 weight oils shear down into the 20 weight range anyway. Most engine wear is during start-up and warm-up period, where the thinner 20 weight oil's flow is desirable. Overall, lab test results of the wear metals contained in used oil samples show low or lower wear with 20 weight than 30 in applications it is specified for. Some ultra fuel efficient and hybrid vehicles are marked to use 0W-20 oil. For some selective mechanical problems with engines, using a more viscous oil can ameliorate the symptoms, i.e. changing from 5W-20 to 20W-50 may eliminate a knocking noise from the engine but doesn't solve the problem, just "masks" it. "

prager

Run 30w straight....the real 30 weight....done!!