If my '77 has "lowish" oil pressure w/ 10-30 Valvoline VR1 and 20-50 seems like overkill can I mix half of each since VR1 conventional does not come in 10-40?? I am not a Petroleum Engineer but I did stay in a Holiday Inn Express last nite!

 

sounds like a plan unless you think its gonna blow up.

 

Thats really helpful !

 

i have done this for years with no harmful effects.my engines go on forever so i sell or give them to friends.some will say not to and that very bad things might happen, but they are the same that will tell you not to use fram oil filters.they are cardboard as you know and fall apart.your choice.

 

I wouldn't mess with it, as all oil from the bottle, is a highly engineered package as delivered. Do what you want, but I'd just live with the formulation, as delivered.

 

From the tech releases I can see, it seems each oil maker has their own formula and in this case the only differance I can see are the "viscosity modifiers" but I am hoping to hear from someone who knows more then me!

 

I did it for 1 season as I was a little over a quart low and had to add, All I had on the shelf was 10-30 and I had 3.5 quarts of 20-50 in the motor and it was a long holiday weekend! Seems to be okay , same oil and formula just different thickness! for lack of a better term!

 

i might want to qualify this a little to say that i only did it between multi-viscosity oils of the same brand as i only used castrol and mobil 1 synthetic.

 

I am also talking about only mixing 10-30 and 20-50 Valvoline VR1. I realize other producers have their own blends designed to work as a system and I do not mix brands or use additives for this reason!

 

I would gladly defer to experts, but in my inexpert opinion all oil is compatible and you can mix it without worries. If your goal is to create a synthetic 15w40 by combining equal parts 10w40 and 20w50 I don't know if you can achieve that result, but the mix should perform fine without harming your engine.

 

Don't worry about it. Are you sure the 20/50 is overkill? It might be exactly what is needed if the clearances are pretty loose. Whatever it takes.

JIM

 

The clearances should be pretty loose as she is approaching 100,000 miles. To answer your question, it seems the majority opinion in C3 is that each of our motors are different and will require different viscosities w/ the major variables being bearing clearances and mileage!
It is also stated that pressure and flow are different things and thinner oils flow better thus lubricating and cooling critical engine parts better then thicker oils. Thus the thinnest oil that will produce acceptable pressure should be used. In my case this would be 10-40 which in my specific case is unavailable! Hence my question!

 

What do you mean by low oil pressure?
How much and when?

Fwiw Ive mixed viscosites if I was a qt low and in a jam....good oil cheap gas station oil, syn with dino and guess what it still ran and didnt explode. Oil is oil

 

I'd leave it with the thinner oil , it'll flow more oil. Buy a $30 new oil pump if the original pump has 100,000 on it.

 

If you lower resistance to flow....bigger clearances, thinner oil etc..you'll have more oil flow at the same pressure. Kick up the pressure with the same clearances and oil and you'll have more flow. Thicker oil with tighter clearances can increase pressure without improving flow...maybe even reducing it. Kick up pressure by reducing clearances and you'll reduce flow...possibly to the point of causing metal contact.You can only flow what the clearances and pressures allow.

You're pretty close..use whatever weight oil gets you the pressures you want for the conditions you operate in. But make sure the thinner oil is capable of carrying the loads you need. There are mega thin race oils(about same viscocity as WD-40!) that can lubricate just fine for a limited time.

100K doesn't necessarily mean worn out....I've seen bearings look nearly new with that mileage.

If you really want 10-40 why not just select another brand? There are tons of suitable choices out there for anything.

As asked,,,what pressures are we worrying about? I'm driving a 200K+ 5.0 Mustang right now that I bought new. Holds less oil pressure than when it was new...but never makes a sound and runs fine without a puff at anytime and hasn't burned a drop of oil since it fired it up after sitting for 10 years (I've put about 2500 miles on it in the last month or two). Don't worry about it too much.


JIM

 

To your original question: Sure.

 

As far as tons of suitable choices, not from Billa's list, at least not in my area! Pressures w/ 10-30 are about 30 at startup then drops to 20-25 at warm idle. It gets about 30 at cruise! With 20-50 it is about 40 at startup then drops to about 35 at warmup and about 40 at cruise!
Cruising rpm is about 2500! I know the 10lbs per1000 rpm rule but I like a hair more, gives me a good feeling and keeps me from staring at the oil pressure gage!

 

I think this whole discussion raises the bar on O/C syndrome. Your oil pressure is fine. Stop trying to out-engineer GM.

 

With Mike Ward!
Run the 10W-30 and don't sweat it. You have about the same oil pressure at cold idle as a new one running 10W-30 with a stock pump and 3x the minimum you need. More flow = better cooling of internals, thinner oil = better cold start protection. I know, its an oil thread.

 

Shhhhhhhhhhhh! Ya'll are going to wake up 540