philacc23

I just bought a 97 accord with 165k miles on it. I want to make the switch from regular to full synthetic on this one. I used to drive a Hyundai and it was common for people with 100k + miles on their cars to have oil leaks when they switched from regular to full synthetic motor oil. Any of you guys have that issue with your Honda or it is all good?

hondapower80

With that high of mileage, you may develop leaks in your car. I would stick to the recommended oil or switch to a high mileage oil and save the cash for future repairs like ball joints, brake pads, struts, etc.

TheMuffinMan

iTrader: (1)

With the risk of what's his face coming in spouting off random things like he does in every oil thread:

At that mileage there is absolutely no reason to switch to synthetic oil, if you do a search the topic has been exhaustively discussed. High mileage oil may cause leaks in the fact it has additives for the sole purpose of swelling rubber seals/gaskets.

If you have no issues and you're not leaking, don't change anything. Run the recommended fluids. You're better off spending your money getting a transmission fluid change, brake fluid change, clutch (if applicable) and power steering flush than you are switching to synthetic.

hondapower80

I should have just posted this link for the OP:

https://honda-tech.com/forums/showth...+synthetic+oil

plugger

Don't use a synthetic oil for an engine that won't benefit from it.

Don't use a high mileage oil on an engine that doesn't need it.

Don't take Muffin's opinion on anything too seriously. :D

TheMuffinMan

iTrader: (1)

Haha there's plugger!

GhostAccord

Bringing this back for a question and testimonial.

So in your opinion what engine would benefit from synthetic?

I switched to full synthetic in my 96 Accord back in 2001. Never had any issues with the switch. Engine temps actually went down a few degrees. When I tore my engine down 4 years later all of the seals still worked and there was no varnish or carbon build up inside the engine. All of the bearings and bearing surfaces where in A1 shape. I'm pretty sure it did what it was supposed to do.

TheMuffinMan

iTrader: (1)

High compression/lower mileage vehicle or Forced Induction vehicles with a fresh rebuild.

I personally say that because after 100k+ miles of dino oil and whatever damage is associated with that, but it'd be safe to say every nook and cranny had dino oil on it at some point it seems unnecessary to suddenly change to a more expensive oil and experience little in terms of gains.

NOW, if you had a 100k+ motor then hot tanked it and rebuilt it from scratch that would be a different story.

Heat

So are you guys saying that he shouldn't use synthetic because he will get no real benefit from it, or because if he does his car will have all sorts of leaks?

From what it's worth, I used to drive a '92 Volvo station wagon, switching from dino to synthetic oil at higher mileage was fairly common on Volvos - there was no issue with leaks with them, at least not from switching to synthetic. However, after you switched to synthetic you were supposed to do another oil change with synthetic after 1,000 miles to get rid of any gunk that was knocked loose, after this second change go to your normal oil change interval.

TheMuffinMan

iTrader: (1)

No, not necessarily causing leaks, but freeing up crud clogging existing leaks

Same with high mileage oils, those additives swell the rubber gaskets/seals for the purpose of clogging leaks but can result in causing them and do more harm than good.

I personally wouldn't be switching to synthetic due to the lack of benefits. 165k miles, all with dino oil, then suddenly have an urge to spend $20 more per oil change for synthetic? Seems silly to me.

Red_Army

where is it that everyone buys there oil and it costs 20 bucks more for synthetic? its 20 bucks for 5 quarts. and like 15 for dino. you saved a filter for buying dino.

still don't think you should switch over in a high mileage car. but bringing money into it is silly. you just spent 5k to build it whats another 20 bucks for nice oil all the time.

TheMuffinMan

iTrader: (1)

Well a quick search on Advance Auto Parts' website shows their conventional dino oil at $2.99 a quart.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_10W-30-Conventional-Motor-Oil-%281-qt-%29-Advance-Auto-Parts_8130005-P_N3253C_T|GRP2046____

Mobil 1 Synthetic same weight is $7.49 a quart, Castrol Edge is $7.99 a quart, Amsoil is even more than that.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_10W-30-Synthetic-Motor-Oil-%281-qt-%29-Mobil1_8020264-P_N4019B_T|GRP2046____

~$5 difference between the two and the Accord takes ~4 quarts = $20 more to use Mobil 1 Synthetic (which really isn't a true synthetic) than dino oil. But maybe I'm just exaggerating on those prices right?


*edit*
And if you are going to use the argument that "oh well that's the cheapest dino oil out there" Mobil 1 10w-30 conventional is still $3.29 per quart. With that you're still paying $17 more

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_10W-30-CLEAN-5000-Conventional-Motor-Oil-%281-qt-%29-Mobil_8140007-P_N3253C_T|GRP2046____

nicolaselias

Thats not a fair comparative as it ignores the oil change specials from advance..

Valvoline oil change specials
Conventional $17 for 5 qt's plus purolator classic filter
Synthetic - $27 for 5 qt's plus a K + N filter which retails for $13.. about 3x the cost of the purolator classic

Mobil 1 Oil change special, $30, including a mobil1 filter worth about $13 as well...

TheMuffinMan

iTrader: (1)

Haha, well I can tell you I got a sale on anything, obviously a "sale" item is going to be cheaper. I was simply defending the fact that if you were to walk in right now, it IS $20 more.

plugger

It's really simple: A new (or in like-new condition) engine that was designed to use a synthetic oil.

Specifically, the engineering tolerances within the engine will be closer in an engine designed to use a synthetic than for a car designed to use a non-synthetic. Why? Because the main difference in a syntheic to a non-synthetic oil is the size of the hydrocarbon molecules. Oils that are derived from distillation of crude oil (i.e. "dino" oils) are a mixture of hydrocarbons, with chains of varying lengths (as are all distillates). OTOH, synthetic oils are more uniform, and have a smaller molecule. The result is that sythetic oils will find their way into tighter spaces between moving metal parts (i.e., will lubricate in engines with tighter engineering tolerances.)

So: If an engine is designed specifically for synthetic oil use (e.g., a modern Porsche), you must use a synthetic, or your new engine will wear much more quickly due to dino oil nor being up to the job. OTOH, if you car is designed for dino oil, the benefit of using a synthetic is much more marginal (synthetics will generally last longer between oil changes, as they degrade more slowly due to the greater consistency of their chemistry.) In general, using a synthetic of the same grade in place of dino will do not harm, but the regularity of your oil changes will be much more important a factor in your engines health than whether you are running dino or a synthetic.

All bets are off for a worn engine. Even if a car engine was designed to use a synthetic, once there is significant engine wear, the benefit of using a synthetic has now disappeared, and you may in fact simply be burning more oil as a result of a synthetic moving more freely through those yawning chasms that were once tightly speced engineering tolerances. In this case, using a synthetic is simply an (expensive) exercise in futility. The correct oil to use a case like this is a heavier grade oil, and perhaps one with "high mileage" additives that are designed to at least partially compensate for some of the issues in a worn engine.

Finally, the reason that a synthetic oil is good for a new engine with tight tolerances is also the same reason people might report oil leaks going from a dino to a synthetic -- the synthetic oil can (and will) find its way more readily through tighter spaces (in this case, the gap between your oil seals and the sealing surfaces.) An oil seal that doesn't leak with a dino can start to leak with synthetic, and it's not just grunge getting cleaned away. It's simply the fact those smaller molecules can squeeze through a seal gap that dinos won't.

So, it's always a matter matching up a grade and type of oil that is suitable for the current condition of your engine. If your engine is new (or enjoys tolerances in like-new condition), your owner's manual recommended oil is your best bet. If your engine is worn, you have to have a slightly deeper level of understanding to choose the most suitable oil for your car.

And BTW, the compression of an engine has absolutely nothing to do with the type of oil you should use. For example, a 1989 Porsche 944 S2 has an 11:1 compression, and was designed to use a synthetic oil. The same year 951 (i.e., a 944 Turbo) has a compression of 8.5:1, and was also designed to use a synthetic oil. Indeed the two engines are very similar, and the design tolerances are in many cases the same or very close (Porsche was one of the first companies to make production cars with engines specifically designed for synthetic oils). And it is the internal engine tolerances that is the key, rather than compression ratio (or anything else for that matter.)

avio

I used high mileage oil in my 98 accord at 160k, nothing bad happened. At a time my rear main seal developed a leak, which somehow fixed itself on regular oil when I went on a LONG 8-hour drive. It was quite surprising, now I'm using the new pennzoil yellow bottle which supposedly cleans upto 40% of engine build-up in the first oil change, no leaks nothing.

Heat

Walmart carries 5 quart jugs of Mobil 1 for about $22 or $23. Meijer (midwestern store) normally has qallon (4-quart) jugs for $20. I've seen O'Reilly's (auto parts store) carry Mobil1 at about $20 a gallon before too, on sale.

For comparison, Meijer also currently has Quaker State (dino) at $10 for a gallon. Personally, I've always used Castrol GTX in my '99 Accord, and Mobil1 in my '09 Mazda5.

TheMuffinMan

iTrader: (1)

Which is why I specifically noted a high compression motor to start with or forced induction

The reasoning behind starting with a lower compression motor for FI is so you can cram more air/fuel in there which as a side effect brings up the compression.

But you are correct, the manufacturer's intended-use oil is what the motor was designed around, and that should be used. My reasoning for stating the high compression and FI vehicles is because generally speaking they see more abuse than say a F22B2 that putters around with it's 8.5:1 compression ratio.

GhostAccord

plugger,

Could you post the tolerances that are used by the synthetic oil running engines? (i.e. the aforementioned Porsche) So that we here on the Honda Tech forum can relate them to our Honda engines.

Muffinman,

If I purchase a synthetic oil and put it in my car and it's suggested change interval is 20-30,000km. I usually went 20,000 km between changes. where as with dino oil your changing every 7,500-10,000km (Honda service manual) So mathematically speaking the synthetic lasts 2 - 3 times longer than regular oils. If this is the case and one was to go buy the manufacturers recommended change intervals. Running synthetic could actually be cheaper in the long run.

TheMuffinMan

iTrader: (1)

Correct Ghost, however with that, did you actually have the oil analyzed for it's "potency" ? It's coming out now that the 3000 miles change is a little on the low side for most oils now. It's VERY possible (based on the reports I've seen from Blackstone) that your dino oil was still in good shape as well even after that interval recommended by Honda. BMW is now giving that free maintenance with like 15k intervals, well what was recommended before that? Same oil as now, just they were not footing the bill, and recommended 7k intervals I believe.

I change my synthetic on similar intervals (5k miles) in the S2000 as I would non-synthetic (5k miles) in my Accord.

If you were to send in your oil to Blackstone they can tell you exactly what shape and condition your oil is in and give you suggested change intervals

Bailonben

Just asking a similar question! Not looking for a whole argument about oils. I recently got a 1992 honda accord with 170k and because ive only had newer engines I wasn't aware about the differences between synthetic and standard oils. And I put in full syn. I'm unaware if the previous owner used synthetic or not but there already was a nice leak on there and I'm wondering if I've done damage? Should I switch back to standard or is it too late? Hopefully some one on here can help me out my roommate chewed me out for using synthetic already so spare me I'm not really trying to ruin anything I'm trying to fix everything up.