cyclist7531

I've recently purchased a 91 vette w/stock L98. According to the previous owner he used dino oil. In my other cars I've always used synthetic. Is there any advantages/disadvantages from switching to synthetic or should I continue to stay with the dino oil. It runs fine, no leaks, etc. I've heard all the stories about leaking, etc. if you switch from dino to synthetic, but would appreciate input from this group. I'm happy using dino oil and doing regular oil changes (car is a weekend driver so won't be putting that many miles on). Also, if sticking with dino oil any favorites? Again, it's been years since I've used dino oil and would like a couple of recommendations of what oil to use in this car.

Thanks,
mark

jrzvette

If it's only used on weekends and you're not racing it, any good quality name brand dino oil will be fine.

The synthetic stuff is good but for your application overkill.

65Z01

When I got both the '88 Vette 6yrs ago and the '88 IROC 4mo ago I switched to full synthetic with no problems.

KeyWestJack

When I purchased my 90 I switched to Synthetic. I just advanced my change schedule the first few times and used a good filter each time, no problems. Its really funny how so many "informed" have fought the use of synthetic. Harley Davidson made all kinds of excuses for years, youve heard them all. Several years ago the finally gave up and now have their own labled synthetic. In the Corvette I have used both Mobil One and Royal Purple. Some swear by Amsoil, in fact I have used it in both of my bikes. Good luck. Jack

B!@cK 86 V3tt3

I have HEARD that switching a motor used purely on dino and then switching to full synthetic may cause leaks in the seals. I dont know how or why but I was just passing it on considering that is your scenario. Something about the different compounds eating the rubber seals away. Not sure but just a heads up for ya.

FYI: I use penzoil synthetic so I am not going against synthetics. I like them as they stan up to higher engine temps.

IRAraid

A few years ago my '86 Blazer (4.3cubic inch=350X0.75) eventually began 'using' oil after it had about 150,000 miles. Consumption slowly crept up to >1qt/1000 miles at 165,000. My dad (who worked in the refining business) suggested switching to synthetic.
It was a miracle!
'Consumption' went down to 1qt/3000 miles. Gave the Blazer to one of my kids who kept it 'till it had way over 200,000 miles and consumption remained less than 1qt/2000 miles.
Good enough for me.
Good luck.
PS it was Mobil 1 and my dad insisted keeping changes at 3000 miles regardless of what oil was used. He said it was contamination via blow-by that ruined oil, not age.

Bad Karma

I run synthetic, better thermal properties.

VenkmanP

If it's a car you're going to keep a long time, then switch. If you're just going to drive it on weekends for a couple years then get rid of it, then save the $.

cyclist7531

The plan is to keep it. So, bottom line, it sounds like there is no issues switching to synthetic (such as leaks developing, etc) if the car had been run on non-synthetic. I use Mobil 1 in my other cars so I guess I'll just switch to Mobil 1.

Thanks, Mark

jaa1992

At one time I had an 88 that had a small oil leak around the valve covers. Switched it from dino to Mobil 1, leak did NOT get any larger.
Car felt "happier" with the synthetic.
YMMV

Cadder

I've saw a comparison done on Horsepower TV a few years back between the standard dino oil and Royal Purple Synth. They actually showed a small increase in horse power by switching to the synth oil.

C66 Racing

Synthetic Oils and Seal Leakage
There are many myths circulating regarding synthetic oils and seal leakage. Due to the significant variation in synthetic oil base stock, blanket statements about synthetic oils and seal leakage may be inappropriate. Many synthetics have a highly processed petroleum basestock. Others such as AMSOIL and Mobil 1 have a PAO basestock, which tends to shrink seals. And yet others, such as Redline use an ester basestock which tends to swell seals. Most synthetics contain higher levels of detergents, which will clean sludge from seals exposing them to oil.

If you have a clean engine and you are experiencing no leaks, then you should not have any leaks with AMSOIL or other quality synthetics. On the other hand, if the engine contains sludge due to age or inappropriate maintenance practices, you may experience a temporary leak. When the seals have gone for sometime without oil contacting and nourishing the seals due to blockage from sludge, they will harden and shrink. Since most synthetics, including AMSOIL, contain a significant amount of detergents, they will clean and remove this sludge exposing dried out seals to the oil. Depending on the synthetic oil used, this leakage may or may not be temporary. AMSOIL uses other additives such as Ester which will improve the seal’s suppleness and counters the shrinkage of the PAO basestock Based on reports I've read, AMSOIL should swell the seal 3% to 5%. But, if the seal has a mechanical fault, such as a crack or tear, then AMSOIL can't repair the damage. How other synthetics effect the seals is highly dependent on their basestock.

Z-07 freak

When I bought my `91 I switched to 5w-30 Mobil synthetic. 40k+ miles later it hasn't leaked one drop. The only difference I have noticed is cooler oil temp.

coupeguy2001

I always add 3 quarts of synthetic to the oil at oil changes.
never had a poblem, and I did notice lower operating temps that other friends that used regular ashless dispersant oils

maksim

Can I also ask something . Ee, I do not seem to find 5w30 Mobil 1
anywhere in my area. 5w40 is existent but rare while 10w40 is in abundance . Sticker and manual recommend 5w30 for vette but what about those that I have available here . I heard once about those 40 weight , 50 weight , but that science .. well I do not remember exactly anymore . Maybe somebody can help ?

kalister1

I run Mobil 1 10W30 in my 93 coupe(It's a Ruby) I run Castrol Dino 10W30 in everything else. I change the oil in the Vette once a year, maybe 3,000 miles. I change the oil in the truck 4 times a year, 12,000 miles. For 1 oil change a year why not?

newbecorvetteguy

Generally speaking, use what the owners manual says. If the engine doesn't require it, you're going to change it at every 3 months or 3k miles anyway, or you drive very little and only change it once per year, I don't see any point at all for paying 2 - 3x the cost for the oil. If it's required per manufacturer, you run it hard, or wish to extend the oil change interval, then switching has some merit. Otherwise it's like buying a hammer made of gold to drive nails. The gold may have some superior qualities over cast iron...more attractive, conducts electricity better, makes a social statement, ect. For the stated purpose, both would do the exact same thing. A lot of people buy stuff because they want the best. A lot of times the feeling of having the best is all your getting out of it. Synthetic oil changed every 3 months or 3k miles is one of those times. I switched to synthetic in my vette, but it's a daily driver, I drive 60 highway miles per day, and I've extended the oil change interval to 6-7k miles which is still less than the manufacturers recomendation. I noted no change at all in oil consumption, engine coolant or oil temperature, fuel economy, or performance. The advantage I did notice is I'm crawling around under my car 1/2 as much as I used to. jmo

Bossman89

I run straight 30 in my 89 because it doesnt see much cold weather.

Demonic85

I recommend regular Mobil 5W-30. Its not synthetic but is very good at cleaning the engine and revitalizing old seals. My '85 burned oil due to some bad seals that I was going to replace and since I switched to Mobil its stopped burning it and runs smoother too! I used to use Castrol GTX by the way.

BADDUCK

You didn't say how many miles were on the car but if it runs well, and doesn't leak oil I think I would stay with dino. The only reason I could see for you to change to synthetic is if you actually will run in severe service situations or plan to actually extend your change intervals. Otherwise spend the extra on gas. I made this decision on my 1989 I bought this year. I chose Valvoline 10W-30 which should work well for you in CA. Good Luck