I have a 91 with L98 engine and auto transmission. The engine has 55,000 miles on it. It has always used regular 5-30 oil. Will there be any problems switching to a synthetic oil?

 

i'm sure your gonna get various opinions on this but i have been running castrol syntec 10w40 in my 89 l98 since i bought it with no problems.. i do however change it once a year witch is about 4k miles.. so far so good just had the covers off and everything looks clean.. 100k on the car and still holds 30+ psi oil pressure.

 

Go for it. You won't have any problems.

 

Thanks for the info. I thought so but wanted to double check.

 

You may experience some temporary leaking. Nothing to worry about, it should stop. I don't think the seals swell as much with synthetic.

 

I changed to Mobil 1 with about 70k on the odometer. I didn't get any leakage.

 

Go with Mobil 1

 

Its possible to form leaks if you dont already have any. But your engine will be better off.

 

Your engine will die! Dino oil forever.....

 

That's why I said MAY.. Every car is a little different. If you do see some leaking, don't panic. If it's in the garage, throwing some newspaper under it wouldn't hurt.

I was a skeptic on synthetic for a while, but a friend who flies swears by it uses it in all his planes. Also, an uncle in the trucking business put 500K on a motor that just ran synthetic as a test for Mobil when Mobil 1 first came out. He said they tore down the motor it was like new.

Too many people I know, read as believe, swear by synthetic based on their experience tearing motors down after use.

I know it's a big debate, and I rather not get into it. That's my .02 and it's worth about twice that.

 

There is no problem switching to synthetic oil. And as stated, you might get some minor leaks. An excellent brand of synthetic oil that has been tested and has been proven to raise your HP is Royal Purple. But that test included changing all the different types of fluids (tranny, rear end, etc.) in the car to the Royal Purple brand.

Synthetic motor oil is by far superior when compared to conventional motor oil.

 

How often do you change your oil? What type of driving do you do? Where do you drive your car?
Even cars with a well formulated dino oil can get over 500K miles without a major engine overhaul.
Synthetic excels at low temperature lubrication, high temperature lubrication and offers extended drain intervals because of enhanced detergency and superior viscosity index improvers.. The detergency package that offers the extended drain will clean your engine better than it has been previously. IF you had leaks that were being masked by sludge and other deposits, your engine will leak. If you didn't, you won't.

Well formulated synthetics buy you some extra insurance. For me its worth the price.
Which oil... for me its an answer to 3 simple questions
1. Is the oil right for my car this is the API service class and the SAE viscosity . ANY current SAE offering in the recommended viscosity (5W30) will meet this
2. Does it fit where and how I drive my car This is partially answered by the SAE viscosity grade and partially answered by normal or service service definitions( severe means dusty, lots of stop and go, short runs that end before the water generated by combustion is evaporated) and finally how often do I regularly change my oil.
Synthetics offer enhanced protection in serve service and extended drain interval uses.
3. Finally is it a brand I can trust.... that is the subjective question that only you can answer. Personally I prefer Shell, but it is not readily available, so I often settle for Mobil 1. In case you did not know Shell owns Pennzoil and Quaker State.

Remember any major brand of oil even a dino oil that is frequently changed ( 3K miles) is better than any oil that is not regularly changed.

 

I changed over on my '87 at 49,000 miles. Now with only about 1,000 extra miles on it... no problems at all. There is a slight seepage from a back valve cover, but that was there before the switch. Just do it, your engine will thank you.
Brad

 

Hopefully this is jsut sarcasm on Xfired's part...

 

I tried synthetic fluids in everything on my vette, and basically everything leaked.

But my 85 has some cork gaskets and tolerances or seals that maybe weren't designed to keep synthetic in very well.

If I could run synthetic without it leaking out, I would.

 

I use only 5W30 Mobil 1 in my 1990. Since you're talking about synthetic, I hope you don't mind my asking if you've seen any 30 weight synthetic oil anywhere. I just bought a new $1,200 log splitting machine and the Briggs-Stratton engine requires 30 weight synthetic oil. I've checked with NAPA, Advance Auto and Wal-mart. They don't sell it, and they're not sure it even exist. I went to a Super Wal-mart today. It was incredible to see all the brands of sythetic that they sell.

 

isn't 5w30 considered 30 weight or am I way off here?

 

Check out this website and give them a call. They are more than helpful. And their prices include shipping. I found their prices cheaper than Napa because there's no taxes added on to the cost.

www.karlracing.com

 

I would consider 5w30 a suitable substitute for straight 30 weight.

To address the original question, there should be no problems going to a synthetic. Many people report an increase in leak rate, but who has any scientific proof?

Larry
code5coupe

 

I switched mine at 152,000. - No problems now and I'm up past 168K.