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What RPM to drive when facing oil problem?


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I wanted to start a discussion with those with mechanical minds, and hopefully not have it become an argument. TO THE INTERNET!!!
My little poor old 4k is on its last legs until its rebuild which should happen beginning of next year.
To keep oil pressure up while driving over the mountains, when it all gets hot, ive had to add an oil conditioner product which did exactly what it claimed to do.
I put in 3 litres of new mineral 20W-50 and stuck in about 300 mls of this additive stuff. without the additive, my cheap gauge wasnt registering a thing driving up hills all the way to about 3500 rpm.
After putting it in, i was getting some oil pressure back and that has got me by.
It has got me wondering what peoples opinion is of driving with oil pressure problems.
Pretend you were on mars, and in order to survive you had to make your 4k powered mars rover get you back to the base station 2000 km away. If you damage the engine you will be left to die.
Would you feel better driving at higher RPMS and actually seeing some oil pressure, or would you take the mentality that lower rpms generate significantly less heat in the main bearings?
I'm stuck on this.
My thoughts:
Lower rpm means more pressure on the bearing at any particular time compared to shifting up a gear (mechanical advantage)
Lower RPM means cooler bearing and oil temps according to all engineering documents ive ever read
Higher RPM give more oil pressure when a pump is failing or main bearings are beyond service specs

I just don't know what is theoretically better for the engine, and would like to know if any of you have ever been in a similar situation and wondered what your driving habits were.


Edited by rebuilder86
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I’m thinking higher rpm is the exact opposite of where you would be going. My trusty 2T in my TA22 years back was struggling, but after a can of slick 50 it was reinvigorated. It was smoky and not good beforehand, and great for years afterward. 

But oil pressure in a can? I can’t see it holding up for long. 

Welcome back by the way

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Hi Jeremy,

                  I read your post an hour ago, but have just stopped laughing long enough to respond, after reading the reference to the "4K Powered Mars Rover".

Been there done that !  Not Mars, but in outback NSW (dirt roads), with a very sick engine, on the second day of a 10 day excursion.  Low oil pressure;  Summer;  But worse than that, was the tick, tick, tick, tick, of a big end on the way out.

Filled it up with the thickest oil I could get hold of, & finished the trip (3000 klms), & got the car back to Sydney.  I remember contemplating what you are presently, & asking myself the same questions.

What worked for me, was to drive which ever, which way, to put the lowest load on the engine. That meant lower speeds & light on the pedal on flat long straight roads, & revs & lower gears to lighten the load, when there was a hill.  Lightly loaded engines don't run as hot.

Never used one of those oil additive products, that increase the viscosity. Sounds good.   Assembled an engine wet once, with a oil made up of 50% engine oil, & 50% molybdenum disulfide.  Rubbed it into the bores, and all bearing surfaces.  Worked a treat !  The MDS is very dark in colour, & 10 years later I dissembled the engine, & was washing the bearing shells & bore with a mixture of kero & petrol, & the cleaning fluid was going very dark, very quickly, until I realised the MDS was being flushed out of the grains of the metal.

Cheers Banjo  

Edited by Banjo
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1 hour ago, parrot said:

Another thought, if you were on mars with zero gravity, would you even need an oil pump?

Thats an interesting question now... 

I dunno, to replace fluid that is ejected out of the bearing journals???

Are u suggesting we should move to space? It probably makes more sense than staying here.

Just managed to put the ring on the missus so well be outa here soon hopefully, so space could be an option.


Banjo, yeh i felt guilty driving along the flat roads trying to be gentle on the engine, because being gentle meant coasting in 4th and not seeing anything on the gauge. Therefor it felt better to drop to 3rd and see something on the gauge, but then id think about the speed of the crankshaft and jump back to 4th haha. I couldnt make up my mind, hence this post. I kept thinking, i wonder what someone else would so.

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Hi Jeremy,

                  The thing I like about mechanical systems, of any description; is that they more than often give you a warning, in advance, that something is amiss, or on the way out.

Unfortunately, electrical & electronic systems are often not as providing, & just go bang, or bust, or splat !

If you suspect something, whilst driving, I always turn the radio off, close the window, to remove wind noise, & listen carefully to the engine, under different load conditions.


Just managed to put the ring on the missus so well be outa here soon hopefully, so space could be an option.

Congrats !   Elon Musk is current selling tickets to space.  However, not 4K powered, which I know will disappoint you ! 


Cheers Banjo


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just out of interest, parrot, you mention lack of gravity and no oil pump...
Do u mean youd just fill the entire engine from sump plug to filler cap with oil haha.
Or are you saying without gravity, the bearing journals clearances wouldn't empty?
Or are you just simply stating that without gravity the oil would splash around everywhere and wouldn't settle in the sump?

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