Has any one notice a difference

[ericsb210]

I have a 78 620 and this is just my point of view I want to know if others have felt a diference as well... So people please post your stories...

 

 

I did a oil change about two months ago I had an Bosch filter and was using the rotella t oil as other members of Datsun recommended using (the oil not the filter). it worked great the only problem the Bosch filter leaked oil From the seal. Today I changed the oil but I decided to go with something different so I went with a "Napa gold" filter and valvoline vr1 oil 20/50. The filter worked great no leaks at all, the only problem is that now I feel that I have less power with the new oil and filter, but with the rotella and Bosch I felt better response and more power .. My question is why am I feeling that ? What might be the cause of this "lack of power" I'm feeling?

 

 

Thanks guys

 

 

You stated in a later post that your oil was dark like usual. Do you drive the 620 often? Two months is not very long between oil changes to warrant an oil being "dark", unless this is a daily driver.

[Ranman72]

I have an agressive cam in my L motor and Rebello Racing recommends oil with more ZDDP in it , or a ZDDP additive

I will trust the race motor legend  

[DanielC]

It is true that the spring pressures, and therefore the pressure between the camshaft and lifters on a small or big block chevy are higher than the pressure between the rocker arm, and cam on a Datsun L engine.

however, the lifters in a chevy engie should rotate, and that reduces the wear between the cam and lifter.  L engine do not do this.  the contact between the rocker arm and the cam never changes.  Make sure you are using a higher ZDDP oil in them.

[HRH]

Yep, hence the diesel oil with more zinc than standard.  I wonder how hard it would be to make roller rockers for the L?  I don't think I've seen that done.  Not that it's necessary, but it would be pretty slick.

[DanielC]

To make a roller rocker arm for a L engine, you would take a rocker arm, and clear out a space where the contact pad is, and put a roller bearing there.   That would remove metal from the center of the rocker arm, making it weaker.  Notice a L rocker arm is thickest, about in the center?

[HRH]

Yeah, I thought about that after looking at some Chevy roller rockers.  Like I said, it's not really needed anyway.  I've been beating the piss out of L valvetrains for a while and I haven't had any failure.  Probably means I haven't tried hard enough. ;)

[banzai510(hainz)]

I wonder how hard it would be to make roller rockers for the L? ???????

 

yes there was a place back east that made them. pin might bust

 

20/50 and running slower? hard to believe.

Datsun book used to say 20/50 in these things. a different brand 20/50 can be less thick. yes I tried this. But the oil leak can happen if the seal gets stuck and double stacks as the old one is left on there

 

rockauto has the nice blue nissan type cheap. Buy 10.

Napa/wix is highly recommended

[datzenmike]

So do you know if the zddp level on the valvoline is higher than the diesel oil?

 

Also do you guys think I should change it right away? Or will it be too hard on the motor? The valvoline oil was expensive and I don't want to just toss it.. I want to run for at least 4 weeks before I change it

 

Thick oil is not going to harm an engine. Drive it as long as you want.

 

 

Foamy oil with largish bubbles on the stick, could be over filled. Brown shaving cream foam on the valve cover fill hole could be moisture so check your PCV valve and the block vent hose is not plugged.

 

Coolant in oil usually presents with a coffee with cream color.

[Scgreen620]

You stated in a later post that your oil was dark like usual. Do you drive the 620 often? Two months is not very long between oil changes to warrant an oil being "dark", unless this is a daily driver.

I use it 6 days a week .. But there was no signs of bubbles

[Scgreen620]

Thick oil is not going to harm an engine. Drive it as long as you want.

 

 

Foamy oil with largish bubbles on the stick, could be over filled. Brown shaving cream foam on the valve cover fill hole could be moisture so check your PCV valve and the block vent hose is not plugged.

 

Coolant in oil usually presents with a coffee with cream color.

I do t have a pcv valve the previous owner took the pipe that goes from the engine out so no pcv valve...

 

 

Well the color was just regular brown I would imagine the cream color on the oil would be visible on the oil cap it self? I might be wrong

[Scgreen620]

I wonder how hard it would be to make roller rockers for the L? ???????yes there was a place back east that made them. pin might bust20/50 and running slower? hard to believe.Datsun book used to say 20/50 in these things. a different brand 20/50 can be less thick. yes I tried this. But the oil leak can happen if the seal gets stuck and double stacks as the old one is left on thererockauto has the nice blue nissan type cheap. Buy 10.Napa/wix is highly recommended

Good to know I should of looked at the manual.. I forgot I had that haha

[datzenmike]

Get the PCV system connected and working. It draws humid air and combustion gasses out of the crankcase that condense and mix with the oil. Your oil will last longer between changes and engine stay cleaner.

 

Previous owners are idiots!!!

[ericsb210]

^^^^Truth

[banzai510(hainz)]

when washing a motor and no start is a sighn of water condensation under dist cap.

Even when a fast Snow melt off has cause this in my 521 truck.

 

As mike said try to get the PVC sytem working as stock or close as you can. Dont be like a idiot and plug the hole. Better to have it open than plugged

 

As for the 20/50?

well its more based on tempature.

winter youll run lower numbers

 

But once warm the shit all works pretty good. I have run them all,brands.

10/30,10/40,20/50 mostly chveron, Havoline ,valvoline Quakers state and the ford 15/40 deisel stuff. My cranks never needed resizeing with 100k miles on them

[Scgreen620]

Update: people who said that oil will perform better warm they are correct I had to drive for at least for half an hour until I noticed the better performance .. Weird but true

 

Would the pvc valve actually make my braks work better too ? Because when I brake into a hard stop the motor stumbles until I let go of the brakes then it goes back to normal idle

[ericsb210]

I suspect a brake booster or bypass valve has taken a poop.

[shacks510]

Next time you change your oil, I suggest using Delo 400LE 15/40 diesel oil. Mike will agree too. It's what I use... well... used... but I will be using it again in the future.

[datzenmike]

Update: people who said that oil will perform better warm they are correct I had to drive for at least for half an hour until I noticed the better performance .. Weird but true

 

Would the pvc valve actually make my braks work better too ? Because when I brake into a hard stop the motor stumbles until I let go of the brakes then it goes back to normal idle

 

PCV will not affect brakes.

 

The brake has a vacuum assist called a booster. A leak in the diaphragm would slightly lower the vacuum in the intake and upset the idle.

 

Try this... pump the brakes several times to release any stored vacuum in the system. Step on and hold the brakes on. Start engine. Immediately you should feel the pedal drop under your foot about an inch. The vacuum assist is, at least, working properly.