I recently changed my oil, and I didn't have quite enough oil to top it off so I used HD-30 oil for my last .7 out of 4 quarts total. My car normally takes 5W-30 and after a little research I figured that it would be OK. Unfortunately, my car has a hard time starting up after sitting for a while now. I have to give it some gas to get the engine started up, which I'm concerned may be a sign that it wasn't a good idea to use this oil. On the other hand, I've read that it may just be the oil cleaning out the car, which I assume would be a good thing. It does spit out some black smoke from the exhaust when it has those difficult starts which I hope is residue being cleaned out. It is a '99 Saturn SC2 with 155,000 miles on it.

  • So it "does" or "doesn't" spit out smoke (please reread your comment as it is confusing)?? Also, what color is the smoke (blue/black/white)? What year/make/model/engine of car? How many miles? Any other pertinent details you are leaving out? Commented Nov 26, 2014 at 11:00
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    HD stands for 'Heavy Duty' not High Detergent Commented Nov 26, 2014 at 16:38

4 Answers 4


While I agree with Allan that you should clean out the oil and put what is recommended into the system, I think the problem is not the oil. I think you might have a leaking injector causing your hard start/black smoke on start-up issue. This is the reason I asked about the color of the smoke, as it makes a huge difference in the diagnosis. If you run some decent fuel additive through you tank (such as Seafoam, Royal Purple, or BG-44k), I think you'll see a marked improvement in how it starts. You may also try cleaning your MAF and throttle body and check to ensure the air filter is good. I'd need to know when the last time the O2 sensors and spark plugs were changed to tell you if you might need to replace those as well, but in most cars, the recommended change interval is around 100k miles.

  • I'm concerned that the smoke might actually be blue, although it doesn't smoke much now, what is the case if it is?
    – ShaneBird
    Commented Nov 29, 2014 at 23:56
  • Why don't you find out if the smoke is blue, then I'd have you ask a new question and we can answer that ... you are trying to open a can of worms which you really don't need to at this point. I still think your issue is separate from putting the wrong oil into your crank case, it just decided to show it's ugly head after this happened or you actually noticed something which had already been going on. Commented Nov 30, 2014 at 0:01
  • Sorry, it's just hasn't been smoking anymore. This problem certainly didn't happen before the oil change but I did just replace the starter also but I didn't think that would cause the problem although I may have been wrong.
    – ShaneBird
    Commented Nov 30, 2014 at 8:41
  • Sorry for the complications, it managed to smoke up yesterday and the smoke is certainly white.
    – ShaneBird
    Commented Dec 2, 2014 at 15:35
  • @ShaneBird ... white smoke usually indicates an issue with water (coolant) leaking into the combustion process somehow. This usually means a blown head gasket or leak at the intake gasket where the coolant travels through it. Commented Dec 2, 2014 at 19:29

HDEO is allowed only if it is SM/SN rated on the container, HDEO is better because it can take the rigors of Diesel use.


HDF-30 as I understand it is for for engines like that found in tractors or off-road plant. Whilst not saying your starting and smoke is directly attributable to the addition of this oil (25%) I would think that it quite probable. Use an engine flush treatment whilst replacing this mix with its correct oil to put your engine on an operational safe side, even if only to eliminate any doubt.


Single grade oil is thicker than multigrade when starting a cold engine, more so as the temperature gets colder. In cold weather this might result in labored cranking and slow starts.

Once warmed up, a 30 weight is a 30 weight.

Engine oil cleaning should not result in noticeable changes in exhaust.

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