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Oil change interval question

Ruby Fan

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Oct 7, 2004
Messages
189
Location
NY
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1985 Black Beauty Coupe, 93 Ruby, 96 CE vert
I really don't use my 93 at all, I use my '85(please don't think I'm bragging). Last year I changed the oil/filter, synthetic as required, and put in gas treatment. I haven't started the car in a year. I know what GM says, but do you folks really think it's necessary to change the oil?. The car is kept in a garage, under a cover. Thanks.:w
 

LLC5

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Joined
Sep 28, 2004
Messages
2,299
Location
Wa.
Corvette
98 black 6spd convert.
I really don't use my 93 at all, I use my '85(please don't think I'm bragging). Last year I changed the oil/filter, synthetic as required, and put in gas treatment. I haven't started the car in a year. I know what GM says, but do you folks really think it's necessary to change the oil?. The car is kept in a garage, under a cover. Thanks.:w



I would me more worried about the fuel sitting for a year than the oil. Start it and drive it through a full tank of fuel and fill it up as soon as possible.

I would change the oil just because condensation does occur in the crankcase even if the engine is not run and the vehicle sits in a garage under a cover. You may not have a problem if you decide not to change the oil since it was never run, it's just that I would not take the chance myself. Good luck either way. :)
 

Hib Halverson

Technical Writer for Internet & Print Media
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Jan 10, 2001
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CenCoast CA
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71 04 12 19
If you haven't run the engine since you changed the oil, I wouldn't worry about it for another year, however, I agree with "LLC5"...be worried about the fuel.

Is the gas tank full, empty, half....what?
 

Ruby Fan

Well-known member
Joined
Oct 7, 2004
Messages
189
Location
NY
Corvette
1985 Black Beauty Coupe, 93 Ruby, 96 CE vert
I took out most of the gas, and I plan to put in a mix containing, star-tron(for ethanol protection), another stabilizer and 2 cycle oil(suppose to be good for the injectors. thanks much, won't change the oil.
 

vetteboy86

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May 26, 2003
Messages
2,760
Location
IN
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1986 Black "Indy 500 Pace car replica"
I've never heard of anyone putting 2 cycle oil in the gas tank becasue it was good for injectors. I would hold off on that.
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
The most important thing you can do is what was first suggested and that is to run a tank of gas through the engine. But not in short trips take it out and drive it a min of 200 miles just cruising without shutting it off.

If you do this you will completely warm the oil and that will get rid of the condensation.

Don't forget that along with the engine sitting a long time the transmission, the wheel bearings, the differential, the u joints, the brakes calipers, etc have all been sitting gathering the same condensation you are worried about damaging the engine. As for the bearings and tires they have sat on one spot with the weight of the car on them for a long time and need to be rotated and heated up by being driven. This does't even get to the cooling system that has been sitting and getting stagnant from not being keep hot. In my opinion a car that has sat for a long time is still deteriorating and can be more trouble then it is worth. There are more things happening to your car then the oil damaging the engine because it has had the oil in it for a year.

I don't think you need to ad all that stuff to the gas. A fresh tank of premium gas has enough additives and cleaners to clean the injectors. If not then they will have to be replaced. While I am thinking about it there is one thing you might do before gassing the car up and driving it. Pull the fuel pump and look into the gas tank to make sure that condensation has not got a lot of rust in there to be picked up by the fuel pump. If it is clean put it back together and drive. If not the answer is obvious you will have to clean it up and replace the fuel filter also to keep from fouling the injectors. Good Luck.

While the car is stored under cover put some d con or moth balls or dryer fabric softener sheets throughout the cars interior and under the hood to discourage the mice from sitting up home using the wiring and upholstery for bedding.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
I took out most of the gas, and I plan to put in a mix containing, star-tron(for ethanol protection), another stabilizer and 2 cycle oil(suppose to be good for the injectors. thanks much, won't change the oil.

What you herd about "2-cycle oil" is a myth. Pouring engine oil in the fuel tank will not clean injectors...at least not very well. It also decreases the octane of the fuel and may foul spark plugs...depending on how much 2-cycle oil you add.

If the injectors are fouled with deposits from bad fuel, carbon fouling or other issues and they've been sitting for a period of time, a detergent-based injector cleaner may shorten or enhance the cleaning process because dedicated injector cleaners have a much more aggressive "dose" of detergent than do gasolines, even tip tier gasolines.

If you want a pour-in additive which is "good for injectors" use one of the detergent-based injector cleaners on the market. They are not as common as cheaper, less-effective, solvent-based injector cleaners, so read labels. Examples of detergent-based cleaners are Red Line Complete Fuel System Cleaner, Chevron Techron, and Lucas Fuel Treatment.

I have never heard of "star-tron" but it is true that injectors on pre 1990 Corvettes can be damaged by contemporary gasolines having a 7-10% ethanol component. A 93 will not have trouble with ethanol-blended fuel damaging the injectors. The injectors might have other problems, but ethanol damage will not be one of them.

What can happen if the engine has been sitting for a long time, is the injector internals can rust because of the moisture in the fuel. If you have a problem with rusted injector internals, no gasoline ("top tier" or otherwise) and no injector cleaner can repair that. You'll have to replace the fuel injectors.

Here's what'd I'd do...

You've already sucked out most of the bad gas and that's a good thing.
Change the fuel filter.
Refill the tank with fresh gas and add a whole bottle of Chevron Techron or Red Line CFSC then drive the car far enough to use that tank of gas.

When you're done with that, run the fuel pressure tests in the FSM to verify the injectors are leak free and that the fuel pump has no internal leaks.

If the fuel pressure test fails and you verify the pump is good, you may be looking at a injector rust problem. See the Factory Service Manual's information on fuel pressure tests for more details.

Good luck.
 

froggy47

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Joined
Oct 24, 2002
Messages
1,000
Location
CA
Corvette
Black 1996 LT4 Coupe/ 2004 Z06/Z16
I had a 96 that sat on a lot for quite some time b4 I bought it. There is a metal tank with a liner. Mine eventually got several pin hole leaks in the liner & metal tank & was leaking gas onto the garage floor. Had to replace tank. Unusual, but it happens. Somehow moisture got between the tank & the liner & rusted the holes.

Long term storage is not good for any car for all those reasons previously mentioned. Better to take it for an extended drive every month or two.

:beer
 

Ruby Fan

Well-known member
Joined
Oct 7, 2004
Messages
189
Location
NY
Corvette
1985 Black Beauty Coupe, 93 Ruby, 96 CE vert
I also own a boat, and because it has periods of 'down time', the ethanol content in the gas may separate the water/moisture out of the gas and cause problems. So, for boaters, a preventative is added, such as star-tron(not expensive at all) to prevent the ethanol from doing this. It also acts like a fuel stabilizer. The 2-cycle oil idea came about from 1)reading it here somewhere and also 2)the boat manufacturer recommends adding a concentrate of 2-cycle to 'fog up' the engine for winter storage. It lubricates the cylinders & injectors. BTW, the engine is a GM 350 block. Just for kicks, the brand of the boat is 'Stingray' :D
 

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