Just put the wrong oil in.....have a road trip tomorrow. Cancel or let it rip?

Grumpy Bear · November 28, 2019

13 hours ago, 2kwik4u said:

@Grumpy Bear Thanks for a more complete picture of how viscosity works.

Do you have a formula available for calculating film thickness vs viscosity at a given temperature? I'm certain it's not as simple as a single formula, but would be interesting to plot that data for given interfaces and see how the film thickness is affected.

Also, any comments on the validity of putting an oil cooler inline with the filter? i was |..| that close to doing that on my TBSS in an attempt to keep the engine cool while towing with it. Thing blew a head gasket (probably due to previous owners rebuild capabilities), and I traded it away for my Sierra. Thought was to run a small trans fluid cooler in one of the brake ducts in the front fascia, and plumb that into an oil filter bypass fitting, and use a remote mount filter at the same time. Would have increased capacity slightly, and cooled the oil a bit along the way. The Sierra doesn't maintain nearly the high revs that the SS did, and it's a smaller engine overall, so I haven't been as worried about it, but am curious your take on the situation there.

Thanks again!

Sent you a PM.

TrailLaser · January 20, 2021

On 11/22/2019 at 7:09 PM, 2kwik4u said:

Just changed the oil in my '15 Sierra 5.3. Oil spec is 0W-20 per manual and fill cap. Realized I was using 5W-30 as I was pouring in the 8th quart.

I've read of the DoD lifters having problems. How sensitive are they to pressure changes from oil viscosity?

Do I need to change before a 600mi road trip tomorrow, or am I good to go?

Gut tells me it's no big deal, head tells me that 0W-20 was spec'd for a reason and I shouldn't mess with that.

Anyone have any thoughts?

My truck loves it in this Texas climate, I only run Mobil 1 annual protection 5w-30 with a XG10575 filter for 8k mile intervals. I'm due for a change in the next 500 miles, just checked the stick, this oil still looks new and the truck is running strong.

To answer your question, it will be just fine, run it and don't give it a second thought.

Grumpy Bear · January 20, 2021

On 11/27/2019 at 10:11 AM, 2kwik4u said:

@Grumpy Bear Thanks for a more complete picture of how viscosity works.

Do you have a formula available for calculating film thickness vs viscosity at a given temperature? I'm certain it's not as simple as a single formula, but would be interesting to plot that data for given interfaces and see how the film thickness is affected.

I do not recall if I ever got around to sending you a PM on this.

It's called the Stribeck Curve. The Hersey number is the formula you're after. While it is quite straight forward the gathering of the data is not, the answer "non dimensional".

The Hersey number is the dimensionless number obtained from the velocity (m/s) times the dynamic viscosity (Pa∙s = N∙s/m2), divided by the load per unit length of bearing (N/m).

The other axis of the Stribeck is the coefficient of friction. The resulting number given in the Stribeck is:

A multiple of the amplitude of surface roughness.

No matter how well finished a surface is, it has asperity. This statement alone should jog the noggin into understanding that the viscosity required FOR A GIVEN SET OF CONDITIONS is about how well the surfaces are prepared. Makes my teeth hurt to hear people say 'because of tighter tolerances". Look tolerances up. It's a statement of precision not dimension.

A foot is a dimension. Plus or Minus an inch is a tolerance.

The question then becomes not "Do I have enough viscosity" but rather "Do I have enough viscosity for the conditions set out in Stribeck". That is not as complicated as it may sound. Why? Because most of the conditions set out in Hersey are fixed by designs of the system and the environment it is constrained by. Things like Speed limits v gearing. Ambient temperatures. Surface finish. Water temperature. Maximum load (towing/hauling). The one factor the operator has an influence over is the oils temperature and as temperature is THE factor that determines viscosity......

How do I have control over the bulk oil temperature? Four ways. 1.) Your right foot & tire, gear, load choices 2.) Choice of water thermostat throttling temperatures. 3.) Additional cooling or blinding. 4.) Trip distance.