50 weight oils

[Patman]

I get this a lot from some of the f-body guys I talk with on the internet, they seem to think that the 20w50 and 15w50 oils out there will offer better engine protection for them, as they seem to think that thicker oil means longer life.

I usually tell them that thicker isn't always better and if the engine wasn't designed with the thicker oil in mind (looser clearances) and the oil pump and oil passages weren't designed this way, then you could end up doing more harm than good.

Comments?

 

[VaderSS]

We have a guy running a stock lower end nitrous boosted 425NA/587N2O HP LT-1 350. He has made thousands of 1/4 mile passes and has 64k on it. He did a recent leakdown which was well within spec. If he had any bearing problems, I think his engine would not last long. His oil? 10W30 Valvoline dino. If it's designed for 5/10W30, heavier oil is not needed.

 

[Patman]

I agree, I know a lot of guys with heavily modified LT1s and LS1s that run good old 10w30 and have no problems. But there is still always those few that think the thicker oils are going to protect their bone stock cars!

It's up to us to edjamacate them!

 

[JonS]

quote:

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Originally posted by Patman:

if the engine wasn't designed with the thicker oil in mind

Comments?

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How can an engine be designed for a certain viscosity? My boat engine says to use 40w. But in colded climates, (32-50) to use 30w, and -32 to use 20w-50. The engine temp is controled by a thermostat, mine is controled to 140-160 regardless of the air or water temp. In a car, isn't the engine temp controled by the thermostat? So it will always be 195-210?

 

[Patman]

quote:

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Originally posted by JonS:

How can an engine be designed for a certain viscosity?

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Now I'm not an engine builder by any means, so forgive me if I'm wrong, but I always thought that a race engine is better suited to the thicker oils because of looser clearances in it, while a production engine (at least from the domestics) are more tight so they suit the 10w30 weight best.

quote:

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In a car, isn't the engine temp controled by the thermostat? So it will always be 195-210?

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That's basically correct. My 95 Formula has a 180 degree thermostat and typically runs at about 205F on the highway (verified with scan tool software) My 98 Formula came with a 177F thermostat and typically ran a lot cooler than my LT1, this one ran around 185 to 190F on the highway (also with a scan tool)

 

[VaderSS]

You are talking about straight weight vs multigrade though. If we were running straight grade oils, we too would have to use different oils for different temps.

Engines are designed with certain clearances. If the engine has tighter clearances, then a lighter oil is called for.

The thermostat partly controls the temp of the engine once it is warmed up. My thermostat opens at 180F, but the fans don't kick on till 220F and 230F, unless the air is on, so the stop & go temp can be up to 230F.

 

[Dr. T]

I will post the chart from my owners manual stating that a 15-50 is the suitable viscosity for temps from -20 C to +30 and beyond....sounds like most of N. America to me....

How do I post pics here...?

 

[Patman]

To post pics, simply click on the code button underneath which says IMAGE, and type the URL of that image into it.

 

[VaderSS]

All engines are different.

My owners manual is very simple when it comes to oils.

5W30 recommended for all temperatures.
10W30 allowed for temperatures above 32F

20W50 and all other grades grades not recommended.

 

[Patman]

My owner's manual is exactly the same as Vaders. Although I think this winter I'm going to go against the recommendations and stick with 10w30 instead of putting in 5w30. If I end up using Mobil 1, their 10w30 has a pour point of -49F anyways. And even if I stick with Maxlife, it's pour point is not bad either, at -36C (not sure what this is in F).

Our winters don't usually get super cold, it's very rare that it gets below 0F, most winter nights it goes down to about 15-20F. This past winter was really mild, most nights it didn't even go below 25F.

My reasoning for not using 5w30 is that I simply don't trust it to retain it's viscosity as long, and I don't like the extra VI improvers. I don't think it'll last for the longer intervals I want to do (I'm saying to hell with my aftermarket warranty and these silly 3k oil changes!)

Here I go again, getting all off topic!

[ June 17, 2002, 04:26 PM: Message edited by: Patman ]

 

[VaderSS]

I've never had problems with 5W30 thinning in my applications, admitedly unstressed V6/V8 apps(and one 86hp 2.0L I4), but the whole point(for me) of synths is overkilling it. So... based on what I have learned here, and the fact that synths flow easily in the cold(and it hardly ever gets below 32 in Houston anyway), I will probably switch to 10W30 after the next oil change(so I can get an apples to apples comparison of tri and supersyn)

 

[Patman]

I was wrong, my owner's manual says I can use 10w30 as long as it's over 0F, so I feel even safer now. I thought it had said 0C and higher, which is 32F.

Besides, the Maxlife 10w30 and Mobil 1 10w30 both have lower pour points than most conventional 5w30s anyways.

 

[VaderSS]

Mine too says 0F. It NEVER get's that cold in Houston.

 

[widman]

Newer engines in general are supposed to be designed with closer tolerances, therefore needing the thiner oil in the cold. Thicker oils will not flow as well through the bearings, nor pump as well to the upper levels of the engine when it is cold. The Ford dealers here use ONLY 5w30 for the entire country even though we have areas where the ambient temp is over 110 F.
I generally recommend sticking with the book until you start to see some consumption,then increase to the next grade as long as the cold range is covered. In my Grand Cherokee I also increased from 15w40 to 20w50 to quite my lifters for about a year until I could get to the states to buy a set. Then back to 15w40.

 

[dave in MD]

BMW and Mercedes recomend very thick oils such as 5W-50

Their engines are probably some of the tightest engines in the world. So I don't think that tight engine theory holds water. Also it gets cold in Germany, so I don't think thats a concern.

Bottom line The Germans may be right about using thicker oils for longer engine life.

 

[Dr. T]

Along the same lines.....looking at Mobil's website, it says that the Ford Cobra R gets 15-50 as the factory fill...what makes that engine different than other stroker push-rod Ford engines already out there????

 

[jjbula]

quote:

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Originally posted by Patman:
I was wrong, my owner's manual says I can use 10w30 as long as it's over 0F, so I feel even safer now. I thought it had said 0C and higher, which is 32F.

Besides, the Maxlife 10w30 and Mobil 1 10w30 both have lower pour points than most conventional 5w30s anyways.

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Doesn't the owner's manual go by the minimum standards for pumpability, pourpoint and CCS? If a 10w30 oil, synth or dino, meets the standards for a 5w30 shouldn't it be good below even 0F?

If so, I bet a 15w40 such as Schaeffer blend should be good to 0F, look at the numbers.

I don't want to blindly go by the manual because it is all about CAFE too. The manufacturer is not allowed to recommend the maximum, or even the optimal, viscosity that a car can use for wear protection.

On the other hand, I wouldn't want to take a 15w40 down to -15F or below, even though the gov numbers may support it.
The minimum pumpability standards (hunch?!) are too lax.

Just trying to find a usable yardstick by which I can choose a cold wx oil. I've always used 5w30 in the past because I don't know any better.

What standards/numbers should I apply?

[ July 30, 2002, 11:11 PM: Message edited by: jjbula ]

 

[Al]

I've used the Mobil1 1-W-30 for years and even though our last 3 Winters have been mild, we had some mornings at -10 to -20 below. 10W-30 was absolutely no problem. As many have said, I feel a 10W is the way to go in syn anyway.

 

[dbrowne1]

quote:

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Originally posted by dave in MD:
BMW and Mercedes recomend very thick oils such as 5W-50

Their engines are probably some of the tightest engines in the world. So I don't think that tight engine theory holds water. Also it gets cold in Germany, so I don't think thats a concern.

Bottom line The Germans may be right about using thicker oils for longer engine life.

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The reason that they recommend "heavier" oils (it's usually 5W40 or 0W40) is because these oils tend to have a higher HTHS value, which is needed for the sustained 100mph+ driving over there. Not needed in the U.S. My VW recommends 5W40 or 5W30 if that's not available, and recommends an ACEA A3 rated oil (which usually requires an XW40 or XW50). I have done just fine with Mobil 1 5W30, as my recent analysis shows.