5 W 30, revisited

I used to believe 5W-30 was too thin but now look at it this way... the 5W part means it's thin enough to quickly flow into the nooks and crannies of an engine when it's still cold. Quicker protection. When it's warmed up,

5W-30 is the same 30 weight viscosity that a 10W-30 is. I got point-of-view this from a Mobil-1 rep who understood I had concerns about 5W-30. I haven't switched from 10W-30 to 5W-30 yet but would have no reservations against doing so after having it explained to me as he did.

Jerry

Don't run 5w-30 in high temps. See the chart in your owners manual.

That's an old wive's tale 5W-30 is 30 weight when warmed up just like 10W-30 is.

Jerry

Sorry, this is what I meant to say.... I was missing the period after 'tale' which changed my intended meaning.

That's an old wive's tale. 5W-30 is 30 weight when warmed up just like

10W-30 is.

Jerry

I use 5W30 in the winter and then switch to 10W30 in the summer. Around here the temp drops below -20C in winter and rises above +29C in summer.

Matt wrote:

I wouldn't bother switching it out, but I would follow the manual's advice at the next oil change. I would think if I did a lot of severe driving in high temps, I would lean towards the 10w30, but if you only do a lot of short trips without getting the engine up to operating temp, then 5w30 may be OK. If a dealer is using non-recommended oil at oil changes, I would think they are voiding warranties! Was the oil they used synthetic? If so, you should be fine until next oil change.

Dana

Manufacturers generally recommend non-synthetic 5w-30 for low ambient temps. Despite the 30 rating, it is less effective and even detrimental at very high ambient temps. Most owners manuals will recommend a switch to 10w-30 in operating conditions which include ambient temps abover 90 F.

Synthetics are another matter. Mercedes Benz, for example, recommends 5w-30 Mobil 1 in vehicles using their computerized Flexible Service System. Depending upon operating conditions (ambient, trip length, average speeds, etc.) can theoretically recommend an oil change interval as long as 20k miles.

Thanks! I'll sleep better knowing that. I was worried about it.

Matt

You really need to understand what the numbers mean....

For hot running, the 30 part is the only important one. 0W30, 5W30,

10W30 and 20W30 and straight 30 are all the same.

The only difference you can make for real hot is to up the second number to 40 or 50.

It is the 0, 5, 10, and 20 before the W that are of concern in the cold with the 0 being the thinnest in the cold temps.

The books give you a 'range' of temperatures to use the oils. If you never get much below freezing 10/30 is just fine.

Here is a link with a decent explanation:

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Jerry McG wrote:

5W30 is OK for cold climates.

I have heard the same thing Jerry. 5/30 is too thin for warm temps, but it makes a great option for cold climates. I have also heard that the difference between the two numbers is am important consideration. If the spread is too wide, then the oil becomes unstable and breaks down.

The Oil Weight Tables in my BMW, among others, seems to support the notion that the 5W oils are ill suited for warm weather. These oils are recommended for sustained temps (weather) like what would be found in Minnesota in winter. I don't think that 5W oils are suitable for California, except they might work well in the mountain regions during winter. I think that the 10W oils, 10w30 and 10w40, can be used year around in almost all of California, but if one wanted to switch to a winter weight oil, then the 5W oils are fine.

Or hot.... Just better for cold.

30 is 30 when hot and that is what either oil is rated for at 100C.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

CRWLR wrote:

From all that I have found, 10W30 is better for warm climates than 5W30.

5W30 is better for cold climates than 10W30.

I agree that 30 is 30, but apparently there is something with theformulation that tends to cause changes.

If I am remembering correctly from when the aeroshell rep spoke with the aircraft engine class I took a year and a half ago, he said that multigrade oils start out as base stocks the weight of the smaller number. I.E. a 5W30 is actually a 5W oil which has had "stuff" added to it to make it thicken to 30W as it heats up, and the 10W30 starts out as a 10W oil. All else being equal, since the 10W30 starts out thicker it will work better at warmer temperatures. Or something along those lines.

I don't really understand the mechanism but the point is that 30 doesn't necessarily equal 30 where multigrade oils are concerned.

---------------------------------------------------- Del Rawlins- del@_kills_spammers_rawlinsbrothers.org Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website:

You are sort of correct.

The best oil for not deteriorating is a straight weight oil. The closer the numbers are, the better the oil lasts. So a 20W30 is a more stable oil than say a 0W30.

I would think like you say, the less work chemically is has to do to have the right thickness the better.

But then we change oil long before it wears out 'usually'. ;-)

Mike

Del Rawl>

I think the whole point is thou, there is more of a range from 5 to 30, than

10 to 30, Hence, the oil has more complex chains of polycarbon thingies which allow it to do that, and hence, it breaks down faster because it works harder and has more complex chains in the system or some such...

just for fun..

most crotch rockets run about a 10w-40, or 15w-50 synthetic mobile 1 red cap. since bikes arn't used below 0 degrees. and 15w is still good down to around -10C or -5C.

You know the really funny part about the ratings is the low number is established or set at 40C!!!! The top number is set at 100C.

We think of the 10 or 5 weight number as being thinner oil at -40C or below 0F, Not above 40C!

Man I am in Canada and we use Celsius or the 'C' in the temps.

40C is really freaking hot!!!

If you look here, it shows what the standards mean: