Oil query

[Mad4slalom]

Hi all , I see a lot on here use valvoline racing 20/50. Oil. But the suggested weight oil is a 5/30 or 5/40. I was previously using the amsoil z rod synthetic . I notice on changing to the 20/50 my oil pressure is higher by about 10psi, anyone else notice this? I am at 75-80 psi cold. ( rebuilt 350 with 6k on motor) is this normal with a thicker grade?

 

[teamzr1]

Due to your engine being rebuilt and has low miles on it
unless racing in hot weather, 20w50 is way too thick in normal engine temps

On a theoretical level, pressure is the result of resistance to flow.
Thinner fluids flow more easily, therefore less pressure is required to move them.
Practically, thicker fluids may result in more pressure but less flow. Worn components result in lower pressures but increased flow.

If you use a thicker oil than is supposed to be in your vehicle, high oil pressure will result and lower the fuel mileage
Could have parts that were not designed for higher pressure and cause of oil leaking
Thicker, will flow slower, causing more pressure by oil pump

I think with no racing and not hot weather, use like a 10w30 in summer and 5w30 in winter

Even GM tells owners of like C7, C8
if racing, put the thicker oil in but replace it after the race to GMs street weight oil

 

[Mad4slalom]

Due to your engine being rebuilt and has low miles on it
unless racing in hot weather, 20w50 is way too thick in normal engine temps

On a theoretical level, pressure is the result of resistance to flow.
Thinner fluids flow more easily, therefore less pressure is required to move them.
Practically, thicker fluids may result in more pressure but less flow. Worn components result in lower pressures but increased flow.

If you use a thicker oil than is supposed to be in your vehicle, high oil pressure will result and lower the fuel mileage
Could have parts that were not designed for higher pressure and cause of oil leaking
Thicker, will flow slower, causing more pressure by oil pump

I think with no racing and not hot weather, use like a 10w30 in summer and 5w30 in winter

Even GM tells owners of like C7, C8
if racing, put the thicker oil in but replace it after the race to GMs street weight oil

View attachment 30410

Thanks Team zr, next question, should I go back to synthetic v rod or any suggestions for a 10 /30 with correct zinc levels.
Also, being in the uk without extreme summer, /winter temperature variations is there not a grade to use all year round ?

 

[Steven Smith]

The only 2 makes I would recommend are Driven and Lucus as both manufacturer a high zinc oil specifically for flat tappet cams, any oil that you need to add an additive is the wrong oil.
Really good videos here:

Camshaft Failure Series

Why did you camshaft fail? We uncover all the details in this series.

youtube.com

 

[Mad4slalom]

The only 2 makes I would recommend are Driven and Lucus as both manufacturer a high zinc oil specifically for flat tappet cams, any oil that you need to add an additive is the wrong oil.
Really good videos here:

Camshaft Failure Series

Why did you camshaft fail? We uncover all the details in this series.

youtube.com

What are your thoughts on viscosity tho, and mineral or synthetic. .

 

[Steven Smith]

What are your thoughts on viscosity tho, and mineral or synthetic. .

I use 10/30 on my C4 with 78k miles.
Mineral or synthetic is a personal choice.
Synthetic is probably the better oil but I really don't think it matters that much so long as it's changed regularly.

 

[Mad4slalom]

Thanks Team zr, next question, should I go back to synthetic v rod or any suggestions for a 10 /30 with correct zinc levels.
Also, being in the uk without extreme summer, /winter temperature variations is there not a grade to use all year round ?

Ps) The guy that built the engine in the usa said a hi volume oil pump was not needed as takes hp but reworked standard pump to improve it , no idea what that entailed tho. should I go back to the amsoil ? i am not liking the gauge so hi . Very hard as everyone has their own favorites and opinions based on a mulitude of reasons . Its a bloody minefield.

 

[Steven Smith]

You can't go wrong with this oil:

Driven HR4 10W-30 Synthetic | Anglo American Oil Company

aaoil.co.uk

Members also get a discount.
I think there was an article in the magazine a few years ago about this company.

 

[Roscobbc]

Ask 10 different people a series of questions about what brands of products they use on their cars..........and you'll get a variety of answers........and so it is with oils.
I'm not going to argue with choices for C4 and newer marques of Vette (so compatively 'thin' oils, and the benefits of synthetic vs mineral) as the later series of engines were designed with tighter tolerances for use with the increased/improved benefits of synthetic oil.
However........ IMHO the use of synthetic oil in an 'old school' C2 or C3 is a waste of money. These engines were designed with larger bearing and component tolerances and the 20w/50's oils of the day were the correct oil to use.
Even a totally re-built 'old school' engine is unlikely to be built with modern-day tolerances that would benefit from a synthetic lubricant. Today most of us only do minimal mileage in our cars, they perhaps lay dormant for several months over winter and we'll generally do an annual oil/filter change before summer use. This is good as it will flush-out any moisture that has perhaps built-up in the oil when dormant perhaps in a damp, cold garage. Mineral oil is generally cheap enough to sensibly that.
Just accept the fact that an older engine using a heavier weight oil during winter driving conditions will take a little longer to 'warm-up' and for the oil to 'thin' and reduce running pressure.
If you really want to use thinner synthetic oil it's OK......just make sure it has the correct PPM ZDDP additive and be prepared for some of those little oil leak marks on the garage floor to be a little larger........if deciding to carry on with 'mineral' oil why not consider a 15w/50 mineral (with the ZDDP)
Me, I'll continue with Valvoline Racing 20w/50 mineral........

 

[Chuffer]

Ask 10 different people a series of questions about what brands of products they use on their cars..........and you'll get a variety of answers........and so it is with oils.
I'm not going to argue with choices for C4 and newer marques of Vette (so compatively 'thin' oils, and the benefits of synthetic vs mineral) as the later series of engines were designed with tighter tolerances for use with the increased/improved benefits of synthetic oil.
However........ IMHO the use of synthetic oil in an 'old school' C2 or C3 is a waste of money. These engines were designed with larger bearing and component tolerances and the 20w/50's oils of the day were the correct oil to use.
Even a totally re-built 'old school' engine is unlikely to be built with modern-day tolerances that would benefit from a synthetic lubricant. Today most of us only do minimal mileage in our cars, they perhaps lay dormant for several months over winter and we'll generally do an annual oil/filter change before summer use. This is good as it will flush-out any moisture that has perhaps built-up in the oil when dormant perhaps in a damp, cold garage. Mineral oil is generally cheap enough to sensibly that.
Just accept the fact that an older engine using a heavier weight oil during winter driving conditions will take a little longer to 'warm-up' and for the oil to 'thin' and reduce running pressure.
If you really want to use thinner synthetic oil it's OK......just make sure it has the correct PPM ZDDP additive and be prepared for some of those little oil leak marks on the garage floor to be a little larger........if deciding to carry on with 'mineral' oil why not consider a 15w/50 mineral (with the ZDDP)
Me, I'll continue with Valvoline Racing 20w/50 mineral........

With you all the way on your comments Ross . I have used Valvoline VR1 Racing Oil 20w / 50 throughout my C3 ownership and do an oil & filter change annually whether I have done a 1000 miles or 5000 miles a year . I get a tad over 40psi at tick over even after a blast on a hot day .

 

[Mad4slalom]

With you all the way on your comments Ross . I have used Valvoline VR1 Racing Oil 20w / 50 throughout my C3 ownership and do an oil & filter change annually whether I have done a 1000 miles or 5000 miles a year . I get a tad over 40psi at tick over even after a blast on a hot day .

I understand that everyone swears by the oil they choose to use, and I stated when I changed the oil last that I was surprised just how watery thin when hot the synthetic amsoil z rod was when draining . I was just worried how much oil pressure I had with the 20/50 valvoline , so is 80+ psi something you would worry about ?

 

[teamzr1]

Ps) The guy that built the engine in the usa said a hi volume oil pump was not needed as takes hp but reworked standard pump to improve it , no idea what that entailed tho. should I go back to the amsoil ? i am not liking the gauge so hi . Very hard as everyone has their own favorites and opinions based on a mulitude of reasons . Its a bloody minefield.

The fact the builder modified the oil pump, cannot relate to what others are using as to weight of the oil
70 PSI while cruising sounds high

Being the engine was rebuilt with newer designs internal parts, you could ask the builder what oil he suggests as
newer parts like piston rings, seals, gaskets, etc may be more suited using a synthetic oil

Due to your driving style, average weather temps, I would go with a 10w30 only for the fact a 5w30 if getting too hot/thin
can become blow by and out through the PCV system, so more oil lose

You have to go by the engine build and not so much as what a stock 350 makeup was.
In any case, with the modified oil pump 20w50 is clearly going to up the oil pressure and also reduce fuel mileage
With higher pressure, it could be the oil pressure gauge fittings are the wrong type (thread and pitch) for high PSI and may need
parts for higher PSI or maybe use Teflon tape on threads o see if that seals better

Just as a compare, my 1999 C5 highly modified LS1 using 10w30 synthetic Mobil 1 oil pressure is from 30 to 45 PSI

 

[teamzr1]

Example of Owner's manual for C6 and newer Corvettes

Also, If oil pressure is still too high, using like a 5 or 10 W
Replace spring in oil pump to reduce the pressure design

 

[Roscobbc]

I understand that everyone swears by the oil they choose to use, and I stated when I changed the oil last that I was surprised just how watery thin when hot the synthetic amsoil z rod was when draining . I was just worried how much oil pressure I had with the 20/50 valvoline , so is 80+ psi something you would worry about ?

On an 'old school' C3 and earlier generations I don't think that 80 psi is too excessive 'initially' on a cold start-up with an engine in good order. 55 - 65 psi perhaps on a cold/mild day at cruise speeds and 40 - 50 on hot day cruises.
'Thinner' synthetic oil is supposed to give better lubricity in modern engines that are designed to take full advantage of it's superior formulation.
Otherwise as Jon at Teamzr1 sez'.