TheSamba.com :: View topic - The importance of choosing the correct oil weight.

Fri Jan 11, 2019 5:34 pm

ramsman wrote: oprn wrote: Quality of the oil has little to do with how often it should be changed. Contamination should be the trigger. Short runs, frequent restarts, rich mixtures, no thermostat, cold weather, heavy throttle foot, high local humidity all contribute to oil contamination and the need to change it regardless of what oil you use.

Correct. There are many different types of contaminants that can enter an engine oil, and most of them have destructive potential. These include water, glycol, fuel, the wrong oil, dirt, wear debris, etc. Solid contaminants are generally referred to as being the most destructive. After oxygen, silicon is the most abundant element on the earth. Silica and silicates (forms of silicon dioxide) make up a large proportion of the earth’s crust in the form of natural soils and terrain dust.

AC Delco Division of General Motors tested diesel engines and found an eight-fold improvement in wear rates and engine life with lower lube oil contaminant levels. In a related study on both diesel and automotive engines, General Motors reported that “compared to a 40-micron filter, engine wear was reduced by 50 percent with 30-micron filtration. Likewise, wear was reduced by 70 percent with 15-micron filtration”. Read that again. That's a lot of motivation for clean oil.

There's a pretty good primer on the effects of contamination and it's effect on motor oils here: https://www.machinerylubrication.com/Read/30697/choose-oil-filter

Most oil filters out there have a micron rating of 10-25 microns, with the smaller micron filters typically causing additional pressure drop across the filter, and it has been that way for many decades. To get finer filtering than that you need to go with bypass filtration. The majors cause of most engine damage I have seen are insufficient oil and insufficient coolant/overheating, followed by water in the oil. Dirty oil and the oil breaking down from use are way down the chart.

Sat Nov 23, 2019 6:05 pm

I'm late here as always. I rebuilt a 1600 type 3 fuel injected engine in 97. It had standard bearings and I used the case and cam and crank and had the heads rebuilt. I used German bearings and rebuilt stock rods.

I have a VDO oil pressure gauge and temp gauge the temp in sump mounted. I always felt the oil pressure gauge was off. I only used 20w50 twice because some site said it was the best. . Since I didn't really know what the bearing clearance was I used SAE 40 Kendal when it still had zinc. Once it dumped the 20W50 which poured out like water I got Valvoline SAE40 . The first thing I noticed it I don't hear the valve clicking right away it takes a few minutes I imagine the SAE 40 it just thicker than the cold 20. Once I drive it in 100 degree southern Calif weather the temp will hit 180*F when it it's in the 80's it will reach 160*F. With the 40 the oil pressure is lower , it starts out at 60 PSI and once at 160*F at idle is 20 PSI yet as I said I feel the gauge in never been accurate even though it does work. The pressure does rise to 40 to 45 PSI @ 2500 RPM.

Nothing on my engine has modified it was the dual relief case and the 26 mm pump which is stock. It's just me yet I never cared for multi grade oil yet thought of going to SAE30 just to see if the temps drop a bit. I've never seen the temp gauge over 180*F I can feel the oil cooler is hot yet not to hot to touch.

I only want to try SAE30 to see if the temps go down. The coldest I drive in is 70*F the oil light takes a few seconds to turn off after a 70* start.

I just go by what the Bentley states and SAE40 seems to be fine for the temps I drive in . My only concern is the engine has 36,000 miles on it and SAE30 might be fine . I don't do high speed trips anymore 50MPH is about tops and it's a 003 auto trans so some heat is from the torque converter cooling fins which is all that cools the trans. I don't have any bearing noise or rod knocks. I'm just old school and feel mono grade oil still have their place. I did get 3 quarts of Valvoline 10W40 and just bought SAE40 Valvoline racing oil since i change it before the 3,000 mark. Just for the zinc. I feel the VDO temp gauge is just a guide not a true temp. I feel Valvoline is good oil and the only brand I can get with higher zine even their regular none racing oil has 890 ppm zinc. I'm not sure if they had a SAE30 racing oil need to check.

Sat Jun 20, 2020 7:05 pm

[email protected] wrote: Jake has it made to HIS SPECS.

Running 5-30 in an engine that has loose clearances and/or oil temps over 240F is stupid. Just as stupid as running 20-50 in an engine with tight clearances and/or temps that don't go over 180F.

If you have temp and pressure gauges, you'll know what to do.

I have to say I keep seeing reference to oil temp and pressure gauges. What brand and type are you talking about here? I have VDO and yes my il temp in in the drain plate yet the pressure gauge is on the cooler. It's not a type 1 or a van and it's not anything other than a stock 73 type 3 FI. I don't know what my bearing clearances are I do know since I rebuilt this engine in 1997 and I used the crank and cam and since it had standard size bearings and was never align bored. I just used standard size bearings and always used SAE 40 with the exception of twice using Castrol 20w50 and just warmed up not fully warmed up the 20w 50 ran out like water . I will say I don't trust the gauges , they are to let me know if I see a change I then know to pull over and have a look. It's never below 65F when I drive and it's been above 100 F. My pressure gauge reads 10 PSI just with the key on and the sender reads above the 10 Ohm it should. I do feel the temp gauge tells me if it's running hotter than it usually is and it never seems to get above 170F in the sump unless it's over 100 and I drive it hard. Then I will see 180F . None of these stock VW's ever had any thing other than an oil light and fuel gauge and a gen light and they did well just by checking the oil and changing it and using the proper weight for the ambient. I may be old fashioned yet I never trusted multi grade oil no matter what is said , it works on the idea of science and chains in molecular structure that alter at temps.

I am far from a scientist , as far as the sun is from the earth and then some. I'm sure the multi grade oils of today are much better than in the days when they came out . I have no issue with those who use them.

For me the info here is useless because it's based on high performance engines. I would however like to know about gauges.

Sat Jun 20, 2020 9:34 pm

hello, what weight oil would you guys recomend for the following,

SR case, 9.5mm oil galleys, 26mm pump, stock dog house oil cooler, full flow. i live in N GA btw. also, does i matter if i use a different weight oil for the break in procedur? as long as its close?

thank you

Wed May 26, 2021 10:20 pm

So I have read through most of this thread. A lot of good, interesting info. I always have used VR1 Valvoline. My engines are all stock 40hp or 1600s. I used 20-50 but read about the oil cooler bypass issue so started using 10-30. I immediately noticed upon start up my engine sounds like it is taking a second to build up oils pressure, I have main bearing noise or rumble almost. This happens on both engines I switched. It seems like the oil pump needs to be primed after sitting over night. I never had this issue with 20-50.

So here is a question, since I am reading pluses and minuses on both sides of the coin using 10-30 or 20-50 how about I used a quart of each on my oil change. Would mixing the two give me 15-40 weight and maybe a good compromise the best of both worlds? LOL Just an idea.

Wed May 26, 2021 10:51 pm

tristanblue wrote: So I have read through most of this thread. A lot of good, interesting info. I always have used VR1 Valvoline. My engines are all stock 40hp or 1600s. I used 20-50 but read about the oil cooler bypass issue so started using 10-30. I immediately noticed upon start up my engine sounds like it is taking a second to build up oils pressure, I have main bearing noise or rumble almost. This happens on both engines I switched. It seems like the oil pump needs to be primed after sitting over night. I never had this issue with 20-50.

So here is a question, since I am reading pluses and minuses on both sides of the coin using 10-30 or 20-50 how about I used a quart of each on my oil change. Would mixing the two give me 15-40 weight and maybe a good compromise the best of both worlds? LOL Just an idea.

You can buy 15w40 off the shelf.

FWIW, I just fired up my T-181 Thing after it sat for 6 months. It fired on the first tick over, had instant oil pressure and was quiet. Would have to look and see what I actually have in the crankcase, but likely either a 0w40 or 5w40. Don't know the full history of this engine, but it has done me well for ten years at 3-5000 miles a year. I assume my bearings are quite tight, though the crank endplay is extreme. I did swap in PC Performance pump with a built in filter which may or may not have bought me some time.

Thu May 27, 2021 12:31 am

tristanblue wrote: So here is a question, since I am reading pluses and minuses on both sides of the coin using 10-30 or 20-50 how about I used a quart of each on my oil change. Would mixing the two give me 15-40 weight and maybe a good compromise the best of both worlds? LOL Just an idea.

NO. The oil companies tell you that you can not mix oil like that to get a custom blend. You could try straight 30W VR-1.

Thu May 27, 2021 3:50 am

Gonna try the straight 30 see if it helps :)

Thu May 27, 2021 7:59 am

tristanblue wrote: Gonna try the straight 30 see if it helps :)

I personally believe these engines like straight 30wt, though the 30wt sold today MAY test out to be more of a 15w30 or 20w30 due to improved refining techniques. Since a straight weight oil is free of viscosity modifying additives which may slowly breakdown, its viscosity should be stable for a lot of hot miles and it should be less prone to forming varnish deposits.

Thu May 27, 2021 8:11 am

vwracerdave wrote: tristanblue wrote: So here is a question, since I am reading pluses and minuses on both sides of the coin using 10-30 or 20-50 how about I used a quart of each on my oil change. Would mixing the two give me 15-40 weight and maybe a good compromise the best of both worlds? LOL Just an idea.

NO. The oil companies tell you that you can not mix oil like that to get a custom blend. You could try straight 30W VR-1.
That must be a joke.... :-s :lol: :lol:

Of course you can mix motor oils, unless your worried it will cause some sort of voodoo magic or something.... :roll: :lol: and yes a good reason to do so would be to adjust oil weight to get your oil pressure perfect or something like that.

What? Is one additive in one oil going to have some sort of chemical reaction with one in another.... NO that is bullshit. It's all motor oil they use very similar addictive packages its all very simple shit... :-k #-o Get real people, the oil companies only say that stuff so idiots don't try to sue them. The disclaimers are in the companies best interest, not the consumers ](*,)

YES YOU CAN SAFELY MIX OIL. DIFFERENT BRANDS, WEIGHTS, EVEN CONVENTIONAL AND SYNTHETIC CAN BE MIXED TOGETHER WITHOUT CAUSING ANY PROBLEMS. HOWEVER JUST BECAUSE YOU CAN DOESN'T MEAN YOU SHOULD.

...of course you could refuse to actually think about yourself and just say "I'm going to listen to the oil company no matter what because they said so" and then never mix oil out of blind fear and tell everyone else they can't as well...

Thu May 27, 2021 8:44 am

evanfrucht wrote:
YES YOU CAN SAFELY MIX OIL. DIFFERENT BRANDS, WEIGHTS, EVEN CONVENTIONAL AND SYNTHETIC CAN BE MIXED TOGETHER WITHOUT CAUSING ANY PROBLEMS. HOWEVER JUST BECAUSE YOU CAN DOESN'T MEAN YOU SHOULD.

You can not mix a 10w30 and a 20w50 and know for sure you are getting a 15w40 unless you do testing on your brew.

Thu May 27, 2021 8:54 am

Wildthings wrote: evanfrucht wrote:
YES YOU CAN SAFELY MIX OIL. DIFFERENT BRANDS, WEIGHTS, EVEN CONVENTIONAL AND SYNTHETIC CAN BE MIXED TOGETHER WITHOUT CAUSING ANY PROBLEMS. HOWEVER JUST BECAUSE YOU CAN DOESN'T MEAN YOU SHOULD.

You can not mix a 10w30 and a 20w50 and know for sure you are getting a 15w40 unless you do testing on your brew.
Yes I'd agree there. I don't advise doing so for no reason but I know that sometimes people will mix different weight oils while recording the oil pressure changes to dial it in. I know of a couple highly experienced racers/mechanics who have told me they do this just to get oil pressure exactly where they like it.

Thu May 27, 2021 1:27 pm

vwracerdave wrote: tristanblue wrote: So here is a question, since I am reading pluses and minuses on both sides of the coin using 10-30 or 20-50 how about I used a quart of each on my oil change. Would mixing the two give me 15-40 weight and maybe a good compromise the best of both worlds? LOL Just an idea.

NO. The oil companies tell you that you can not mix oil like that to get a custom blend. You could try straight 30W VR-1.
NOT true. As long as you use the same brand and the same series of oil there is no problem mixing say a 10W-30 and a 20W50. That said not many companies will have that viscosity range in the same series.
It may not end up exactly as 15W-40 even in "the perfect" blend due to the additive packages, but it will be close.

In the dark days during the late 90´s and early 2000´s where we fought issues with flat cams etc because we didnt really know what was happening to the oils, we mixed 2 different oils to get the behaviurs we wanted, or at least in the neighbourhood. That was a cheap no name oil for gasoline engines and a high end diesel motor oil. Then we learned more, and oils became better for what we wanted, and the vintage oils became better aimed at what was neeeded, or at least some of them. So today you do normally not need to perform such witchcraft to get what you want or need.

Thu May 27, 2021 3:59 pm

Ok, here goes:
Recently rebuilt type4, 2.0L
stuffed in 64 bus engine compartment, so airflow might not be ideal
all tins, including sleds, thermostat and flaps installed.
I'm in the midwest, but I'll probably only drive this thing at temps of 50F or above.
A buddy recommended 20-50 Valvoline racing oil (high zinc), but now I'm second-guessing.
Right now I'm running o'riellys house brand 10-40 :lol:

Thu May 27, 2021 4:08 pm

Alstrup wrote:
In the dark days during the late 90´s and early 2000´s where we fought issues with flat cams etc because we didnt really know what was happening to the oils, we mixed 2 different oils to get the behaviurs we wanted, or at least in the neighbourhood.

I would be worried today that two different brands of oil might have fairly different wear packages and such packages might clash a bit, especially if one intends to run their oil for extended periods of time. I think sticking with one brand is a very reasonable thing to do if one is mixing oils.

I can buy 0w30, 5w30, 10w30, 0w40, 5w40, 10w40, and 15w40 all within one brand of oil so mixing just isn't something I find necessary to do.

Thu May 27, 2021 4:51 pm

Some oil is better than none.

Thu May 27, 2021 5:20 pm

Igpoe wrote: Some oil is better than none.
Best answer so far... lol

Thu May 27, 2021 5:22 pm

Igpoe wrote: Some oil is better than none. Sufficient oil is better than an insufficient amount.

Thu May 27, 2021 8:15 pm

Wildthings wrote: Igpoe wrote: Some oil is better than none. Sufficient oil is better than an insufficient amount.
I feel personally attacked

Fri May 28, 2021 12:34 am

Alstrup wrote:

I would be worried today that two different brands of oil might have fairly different wear packages and such packages might clash a bit, especially if one intends to run their oil for extended periods of time. I think sticking with one brand is a very reasonable thing to do if one is mixing oils.

I can buy 0w30, 5w30, 10w30, 0w40, 5w40, 10w40, and 15w40 all within one brand of oil so mixing just isn't something I find necessary to do.

I don't think you read my original question/post closely. I said I use only Valvoline VR1 for the ZDDP and it's availability for me. VR1 is available 10W-30 and 20W-50 and wanted to mix to make 15W-40. Obviously both oils are the same brand and type and VR1 does NOT come in 15W-40.