Engine oils because "Oils aint oils Sol" (Page 1/1)
ausfiero123 JUN 12, 12:22 AM
Hi again, another question as I learn about my new purchase. The previous owner of this car did not use it very much and before I bought it I believe it had been under cover in their garage for about a year,undriven. So my question is regards engine oils,I see that this has been discussed in the forums but I have a specific question that is- this car has been driven with Penrite 15w-60 fully synthetic engine oil for probably around 10 years as that is how long I believe the PO had the vehicle before selling to me and it has always been limited usage in that time. To me that doesnt really seem to be a suitable oil but I am somewhat concerned about switching to something else now so any advice please.
Mike in Sydney JUN 12, 05:27 AM
I use Castrol 10W40 Magnatec in both of my 2.8 GTs. One has 107,000 miles and the other has ~70,000 miles. Unless you are living ing the Snowy Mountains or the Victorian Alps, you don’t need 5W60 oil.
Dennis LaGrua JUN 12, 08:00 AM
I always use the oil specified by the OEM of the engine. While some believe that higher viscosity oils have a higher film strength and provide better protection I'll stay with the recommended oils.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Vintage-Nut JUN 12, 09:58 AM
GM preferred an energy-conserving engine oil for best fuel economy and cold starting which is the conventional 5W-30 motor oil

But I don't need 5W viscosity as my 'low' temperatures are around 40°F so I use Castrol 10W40 too.

The other topic is petroleum-based oils vs. full synthetic oils.

To me, I use petroleum-based oils because the cost AND I rather change the oil more often than a longer oil change interval.
Patrick JUN 12, 05:06 PM

quote
Originally posted by ausfiero123:

this car has been driven with Penrite 15w-60 fully synthetic engine oil for probably around 10 years as that is how long I believe the PO had the vehicle before selling to me and it has always been limited usage in that time. To me that doesnt really seem to be a suitable oil...



I didn't even know that such a viscosity of oil existed. I looked Penrite 15w-60 up, and I noticed it states... "FULL ZINC additive package for superior engine wear protection".

This is where it would be helpful if people would mention what the heck year, engine etc we're dealing with. Zinc is required for engines with flat tappets (2.8), but not for engines with roller lifters ('85-'88 2.5)

Another vote here for 10W-40 oil.
theogre JUN 12, 06:31 PM
Car likely have other problems and PO used 15w-60 to "fix" it/them.

Example: The V6 version in Fiero, Cavalier Z24, and others have a long history w/ low oil pressure because Crank and Rod bearing going bad but other problems can cause same w/ any engine.

V6, VIN-9, 30-45 PSIG
L4, VIN-R, 36-41 PSIG

Test w/ a "real" gauge.
Oil pressure should stay within the specified range at all RPM. In very cold weather, oil pressure may be a bit higher than normal until the engine warms up a bit.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

theogre JUN 12, 10:21 PM

quote
Originally posted by Vintage-Nut:
GM preferred an energy-conserving engine oil for best fuel economy and cold starting which is the conventional 5W-30 motor oil

But I don't need 5W viscosity as my 'low' temperatures are around 40°F so I use Castrol 10W40 too.

The other topic is petroleum-based oils vs. full synthetic oils.

To me, I use petroleum-based oils because the cost AND I rather change the oil more often than a longer oil change interval.

All "preferred" an "energy-conserving engine oil" w/ API mark saying so for Decades...
Basically mean is thinnest oil at the time.

Current thin oils are 0W-16 0W-20 and 5W-20 as OE but when read Owner's book because many can take 5W-30.
Now KIA and others have dead motors and lawsuits partly because of those very thin oils.

Don't change Engine Oil too often.
3000 miles push by many was BS even in 70's & 80's. Jiffy Lube and others got sued for pushing that crap.
sleek fiero JUN 13, 02:08 PM
I use high zinc 10-30 Lucas oil in my 2.8. Probably a lot of you only drive in nice weather to weekend car shows etc. rather than daily drive which means you probably should change oil more often. I only drive maybe 1000 miles a year and no long trips so I change the oil and filter before I put it away for the winter to get rid of any moisture and prevent possible sludge buildup.
Vintage-Nut JUN 13, 08:08 PM

quote
sleek fiero: I only drive maybe 1000 miles a year and no long trips so I change the oil and filter before I put it away for the winter to get rid of any moisture and prevent possible sludge buildup.




IMO:
Oil change interval is either by 'Miles' or 'Yearly' and on high mileage vehicles, my maximum of petroleum-based oil is 5k miles.
This is another reason I don't use synthetic oils as I'm retired and many of my vehicles get less than 2k miles a year.
If I'm only 'running' the engine as 'in storage', I'll wait longer than changing it yearly.


If YOUR vehicles get 15k miles on the clock before a year, of course use synthetic oil which can last as much as three times longer than conventional oil.

[This message has been edited by Vintage-Nut (edited 06-13-2023).]