I have read alot of what has been the reasoning for using what oil on this forum, and this is what I have come away with. Most all of the guys with high mileage, 100,000 to 150,000, at least on Evos, have been using Castrol GTX 20-50 dino oil in there bikes without any engine work. Also read where the aircraft guys were using synthetic for a while, and then started developing engine problems. They switched back to dino oil.

When I got my 99 Softail Custom last year, it had Castrol GTX 20-50 in it with 17,000 miles on it. I changed it to Mobil 1 VTwin, but I think I will change it back to Castrol. Money is not the issue here, it is simply the fact that EVO's seem to run a long time on Castrol.

If some of you guys with high mileage running synthetic will post your results, I would like to see what you did. I am sure there are some out there that have some high mileage bikes with synthetic also, but it looks to me like Castrol works, and works well. Just my 2 cents.

 

Well, I've got 150K on my '92 FXRS, and I've used Harley-Davidson,Valvoline Racing, Pennzoil Racing, Castrol GTX, Havoline and have used Kendall GT only for several years now- all dino oil 20w50. I also used Quaker State semi-synthetic for one oil change. The only engine work needed has been base gaskets and cams (lifter failures). I change the oil after 2500-3000 miles.
I don't believe syn oil is necessary for anything but an out and out racing engine.

 

There you go MP; The proof is in the pudding so they say. With those kind of results why would anyone use synthetic. Maybe I am just old fashioned, but it seems to me that dino works just fine. I doubt that synthetic would have made it do any better, and maybe not as good. I have heard many stories like yours.

 

First, MP's report is anecdotal evidence, as we don't know the condition of MP's engine, like the state of the compression and oil rings.

Second, MP changed his oil every 2500-3000 miles, which IMO is a requirement if you use dino oil. Synthetic oil resists oxidation better than dino, and any of these can go at least 5k miles between changes. I did two tests on my old RK Evo, one in summer and another in winter, and was told the oil could handle 7-10k miles before the additives were depleted, including those that contribute to TBN. Thus, since you can buy a high-quality synthetic for <$5/qt. (Mobil 1 15w50), there is no monetary reason to use dino oil, which in time will form sludge regardless of the change interval.

Synthetics tend to have better lubricity than dino oil, partly due to superior additives, and that translates into longer engine life. It also adheres to metal better and allows easier starting, which also contributes to longer engine life. Most engine wear occurs in the first few seconds of starting a cold engine, and if there is more residual lubricant on the metal surfaces at that point in time you incur less wear.

To the OP, Castrol GTX 20w50 is an excellent dino oil, and I use it during the break-in period of all my new bikes. The synthetic regimen starts at about 2k miles for me. If was to select a dino oil to use, this one would be at or near the top of my list, but I would not use anything but synthetic in a car or bike that you plan on keeping for years that will accumulate high mileage.

 

Synthetics are better oils for TC88 and 96 engines especially the EFI ones because they run so much hotter than the EVO engines do. However, I would never use synthetic oil in an engine made prior to 1995 as that was around the time that gasket technology was changed to gaskets that would handle synthetic oil. I would also not use synthetic oil on an engine run with dino for morre than 25-30,000 miles.

But Castrol GTX 20w50 is not a real robust oil compared to other oils. If you want a really decent dino oil then try Brad Penn.

www.bradpennracing.com

You have to find a local distributor in your area but it has the best specs for a dino oil I have seen yet. It also has an HTHS of over 6 for the racing 20w50 which is a very tough robust oil.

 

+1 ,,,I agree and will stick with my Redline in all 3 holes.

 

77k on my Twin Cam using dino oil. She still runs like new, doesn't smoke, and doesn't need oil added between changes.....FWIW, I ran HD dino for the first 72k, because I got it from a local deal for $1.99 a quart. When the price went up to nearly 6 bucks a quart, I promptly switched to Valvoline V-Twin....It works for me.

There ton's of opinions and no "right answer" for what is best...I have a friend who has 80k+ on his 2003 Ultra. He uses a famous named, pyramid scheme sold synthetic oil and changes his oil every 10k miles...It works for him.

 

I've always said that all of the usual suspects in the synthetic oil market (Mobil 1, Redline, Royal Purple, Amsoil, even Syn3) are excellent products, and IMO the criterion for selecting any of these would be price and availability.

I've told this story before and will do it again now. About two years ago two friends collaborated to perform big-bore upgrades on their 2000 EG's. One of them had been running Amsoil 20w50 MC oil and the other Mobil 1 15w50 (not V-Twin), which costs half as much. The former had 50k on the clock and the latter 60k at the time. When the jugs were removed and internal parts inspected neither engine showed any noticeable or measurable wear, and even the piston coating was still intact on both engines. The cylinder walls still had the hone marks showing. I dare say that any synthetic oil would have done as well as these, and the point is that you don't need to buy the most expensive oil to get the best lubrication.

 

Yeah, and I've had the cylinders off of my Ironhead with 40k+ miles of riding on them since last boring and the cross hatching was still plainly visible...I use regular Pennzoil 20w-50 in it....It ain't a HD, but I also got to see the guts of my truck's motor last year when a slight headgasket leak got repaired. At 154k miles, she still had the cross hatching in the bores...I use Pennzoil 10-30 in it...........IMO, good regular mainenance using any approved oil, dino or synth will yield long term mileage.

 

As far as I can see, this post is rather old. However, I am a bit surprised that viscosity, vaporization, and heat are the only topics mentioned. I want to pose the question that Harley's have roller bearing engines. When you use full synthetic, it is too slippery and creates a flat spot. Therefore I believe the bearings need something to grip onto. That being said, I would like to know if anyone has a favorite dino oil? Or would a synthetic blend be the best of both worlds?