gw7

Hey guys. I know there is a TON of info on this forum about premix, what two stroke oils to use, OMP block offs, Idemitsu, ratios of premix, etc. etc. etc. and I have read them repeatedly. I'm making this post because some of that information is very old, some of it is very conflicting, and the only info on OMP I could find in the alphabetical FAQ section was a three-part series of posts about the technical functioning of the OMP that's way above my pay grade.

This is also a bit of an odd situation, in that I'll have to source everything in a state I'm not familiar with and cannot perform any work on the car until I am home. I don't know what parts stores are around, don't know their inventory, and can't put a bottle of Idemitsu in my carry-on. So please keep in mind that your recommendations will have to be completely from an Autozone or hardware store shelf.

The situation:

I am flying to buy an FD that was recently imported. I am driving it home, about 10 hours. The car had an oil change a few hundred miles ago in Japan with Sunoco 5W-50. Seller did not specify if the oil was conventional, full synthetic, or a blend. I will be trying to figure that out before I fly up to get the car. It's a unique situation in that I'm in contact with the guy that refreshed the car prior to export, so I have a bit more information than most folks do on an imported car.

To the best of my knowledge, the car still has the stock OMP. I have no idea if the previous owner premixed or not (again, car is from Japan), but the engine seems to be very healthy with only ~55,000mi and good compression numbers. Front: 130 - 123 – 122, Rear: 130 - 130 – 125.

I want to keep the car healthy and happy until I get it home, at which point I plan to do the 0.5oz/gallon premix with Idemitsu, as the factory OMP should still be working.

My questions for the triangleheads on this forum:
1. Should I premix with every tank on the drive home? If so, what's a good readily available two stroke oil I'll be able to find over-the-counter while on a road trip? Is 0.5oz/gal still the preferred ratio for cars with a functioning factory OMP?

2. Obviously, I will be checking the oil level at every fill up too. If the car is currently running 5W-50, I should buy a jug of 5W-50 to top it off with as I go, correct? If I cannot verify synthetic vs. blend vs. conventional oil for whatever reason — what the hell do I do here?

3. When I return home, should I block off the OMP and run straight 1oz/gal premix? Keep the OMP and go 0.5oz/gal premix? Or get an adapter for the OMP and run a reservoir in the engine bay so I don't have to premix? It doesn't bother me to do so, just wondering if one is truly better than the other. I've heard the OMP just kind of "sploots" oil and doesn't spray it like many people think, meaning premix is still preferred over the reservoir.

Thank you for any and all advice. My goal is to get the car home happy and healthy, learn a lot about it, and keep it that way. I owe you all a beer.

- g

Mrmatt3465

iTrader: (10)

Go to Walmart and grab you some of this.

https://www.walmart.com/ip/Super-Tec...allon/16795065

Readily available and will work fine. 1/2oz per gallon with the OMP in place.

If the car is basically stock, you shouldn’t burn through too much oil on the drive back TBH. These inject some oil, but not an exorbitant amount. If it’s full of oil when you start, you will probably be halfway down the dip stick after your long drive home.

IMO, depending on what you want to do with the car will decide how you treat the OMP. Can’t delete it without a PowerFC or an aftermarket ECU or else it will go into limp mode. If I were you, I’d just leave it in place and premix 1/2oz per gallon. The OMP itself is pretty hearty. Just make sure when you tear the thing apart for reliability mods you replace the oil nozzles and lines with new OEM and you’ll never have to worry about them again. SS OMP lines are overkill. New stock is perfectly fine.

Enjoy it.

Matt

scotty305

iTrader: (2)

I agree premix is a good idea on a long trip. Remember you will also need a way to get the 2-stroke oil in the tank, for instance a long funnel that is narrow enough to fit in the filler neck. Get some shop towels and a large ziplock freezer bag (or plastic container) to store the funnel in, because it gets messy after you've used it once. Airlines will let you bring some tools in carry-on, just nothing too sharp. They should be fine with the basic 10mm / 12mm/ 14mm sockets (and a couple of extensions), Philips (or ideally JIS) screwdriver, flashlight, gloves, telescoping magnet, mirror-on-a-stick (I forget what these are called), and maybe some pliers if they aren't too sharp at the ends. Look into buying a Lisle funnel (or equivalent) and few gallons of distilled water locally in case you need to refill the cooling system. Even without a lot of miles I would be most suspicious of the decades-old cooling system. If the hoses are all original they need to be replaced similar to an old set of tires. Maybe get a cheap thermocouple sensor to temporarily tape onto the upper radiator hose, since the OEM coolant gauge is heavily center-weighted and won't move much until temperatures are already dangerous. If you do this, test it out on your daily driver before your trip.

I would look into a backup plan in case your 25-year-old car isn't able to make the entire 10-hour trip. Find the hotels and U-haul/Penske/Enterprise rentals on the route, and hope you won't need them. If they won't rent a pickup and trailer for towing, look into the bigger box trucks since those are usually capable of towing a car behind them.

Sgtblue

iTrader: (16)

Most quart jugs of 2-cycle pour right into the tank, so no need for a funnel imo. And a quart of the stuff should be more than enough to get you home. I usually use the marine low-ash stuff but don’t sweat bullets over it. And just guesstimate based on how much fuel it’ll take to fill up.

I think historically there’s been a gradual change in general forum opinion. It used to be pretty cavalierly recommended to remove the OMP for a RA adaptor, or just premix. A lot of things factor into the decision...street vs track, packaging, level of modification, power level, emissions testing vs no testing, AI etc. A lot has been learned over the years.

gw7

Very stellar advice, thank you all so much for these awesome responses. Good to know about bringing tools on a plane, smart advice on mapping UHauls along the route, etc.

@scotty305 Fortunately, I believe the radiator hoses have been updated (at least the lower has) and the car does have an aftermarket water temp gauge (Blitz, I think – neat add!). At what temp do I become concerned, pull over, and do the coolant dance?

Still looking for opinions on what kind of motor oil to add, worst case scenario, based on what's already in there!

arghx

iTrader: (3)

I'm not in the "Premix all the things" camp. If it has stock ECU, the OMP is most likely working just fine unless it's in limp mode. If it does not have stock ECU it will not go into limp mode (only stock ECU has it). Limp mode is your friend, so is overboost fuel cut, rev limiters, etc. They are there to protect the engine.

In that case of not having a stock ECU (most likely Power FC), you can premix as a precaution.

I've never premixed any of the 3 Rx-7's I've owned (all street cars). It's just a hassle, not worth the inconvenience (can't let anybody else drive it for more than a short trip without giving them a long list of instructions), and there's no guarantee it will extend life on a nearly 30 year old car that could lose a coolant seal next week.

Some people enjoy what I call "rotary rituals" such as premix but they get to be draining after a while.

Sgtblue

iTrader: (16)

If your question is what BRAND, that’s like asking what’s the best beer.
If it’s a mineral vs synthetic question, that’s a perennial split of opinions. And yes, we all know what MAZDA recommends. Search, read and just make up your own mind. Not much history of oil related failures either way. Probably more important is to shorten change intervals a little over what you would in other cars. I think almost all rotaries suffer from some fuel dilution over time, carbon and deposits via the OMP, and then there’s the heat of the turbos.

DaleClark

iTrader: (55)

Premix is fine, but at the end of the day it's a car, you get in and drive it. Mazda designed it that way.

If it will help you sleep better, just get some premix at Wal-Mart when you get there and go for it. As stated make sure you get a funnel to make it easy to pour in. Big thing is don't run TOO MUCH premix or you'll have a smoke show on your hands.

Have a safe drive home, and enjoy the new FD!

Dale

j9fd3s

iTrader: (3)

+1 no premix needed, its just a car. every gas station carries 2 stroke oil, and you don't need that much anyways

gracer7-rx7

iTrader: (16)

The only time I premix is when I'm doing a track day. Otherwise, I don't see a reason for it for street driving.

NightWalker86

Considering the costs of a plane ticket (not to mention the health concerns with flying at the moment), the unknowns with a used car (much less a rotary), and the potential for a lot to go wrong, why not just have the car shipped back home to you? That way you can properly service it, go over everything, and give it a shake down close to home. Seems like it would be much safer all around (for the car and you). Not saying everything won't go perfectly with your current plan (and it could be a lot of fun), but why risk it when it sounds like the cost factor will be about the same? Paperwork and payment can all be done remotely I'm quite sure. Just a suggestion.

Montego

iTrader: (1)

Exactly, unfortunately this forum can make anyone paranoid. Thankfully these cars are not made out of paper so if the car is relatively in stock form, it will be plenty reliable.

To the OP,
After a thorough inspection simply drive the car home without beating on it. Just keep an eye on the water temp & if you see it go above the halfway mark pull over and check things over.

Edit- The reason I say that is because under normal conditions that gauge should never go past the halfway mark. Only once in all of the years I have owned my FD (22 years) I've seen that needle move past center. It was on a very hot day (at one point I saw 108F on a billboard) and I was coming home from a 300 mile round trip. So I was about 220 miles into my trip, had the AC on and was cruising through a valley when I noticed that my stock temp gauge needle rose to the 2/3 point. Freaked the **** out. Turned off the AC and turned on the heater. My temps quickly dropped back down and stayed down even after I turned the AC back on. I assume that I hit a real hot zone while passing in that valley because I've never experienced that again.

Now the reason I didn't pull over right away was because 1) the low coolant light didn't turn on 2) I know my car and it doesn't have cooling issues 3) I hadn't hit scary temps (but very close) and 4) How hot that particular day was. But take away any of those points and I would have pulled over right away.

scotty305

iTrader: (2)

I agree 2-stroke oil is a pain and shouldn't be necessary for a stock car driven gently. But you're taking a long trip on a car with an unknown history, IMHO a little extra caution shouldn't hurt. The factory ECU will trip a check engine light if it detects the OMP valve isn't going to the commanded position, but it doesn't have a way to know if oil is actually getting into the engine. I know someone who worked at a rotary shop and he said they once rebuilt an an engine that ran without functional OMP (and no premix) and supposedly it drove OK but the housings had excessive wear.

For water temps, on cool days I never see much more than 180-190 F when cruising on flat roads, maybe 200 when going up long hills and the turbos are doing work. On a hot day I've seen 215+ with the AC running and the car moving slowly, but it cools back down once moving in 3rd or 4th gear. My guess is low airflow through the single stock oil cooler hurts cooling performance at slow speeds. I hurt the cooling seals on my FD and then kept limping it around for a long time when I was younger and dumber. It would overheat to 230+ degF and spit a lot of coolant and steam out of the overflow tank if I let it run for too long (even at light loads).

For engine oil brand, I haven't heard of anyone having problems with certain brands and talking about it online. The engine does dilute the oil with fuel, so I think it's probably more important to change the oil often than to use a certain brand. If the oil smells strongly of fuel when you check it, you might risk stopping at a mechanic (not a quick lube) and letting them put in some fresh oil. I think the FD is one of the easiest oil changes I've done, the drain plug and filter are both easy to get at.

arghx

iTrader: (3)

For what it's worth, I bought an FD sight unseen from Bring a Trailer in 2017, with a one way plane ticket and then immediately drove it a 1000 miles. It was on the original engine (50k miles but still, 22 years old). The only thing I had to watch out for was the engine oil consumption.

It will likely need all new rubber hoses as a precaution when you get it home. Any of those could leak at any time, but odds are the car will make it back.

Johnny Kommavongsa

iTrader: (13)

1: If it's easy enough for you to get two stroke to premix on the way back, I would premix. If not, I wouldn't be too worried about it.
2: I would think it has conventional oil and would buy the closes weight it currently has at a gas station after you get the car.
3: I haven't had any experience deleting the OMP but I personally would just keep it and premix .5 ounce per gallon if it's just a street car

Here in Nashville,TN it gets pretty hot in the summer and I like to use castrol 20w,50 conventional oil.

I have also bough a 1 ticket to pick up a car around Detroit and drove to Nashville. A few weeks later, I took the same car to Jacksonville, FL, a car meet somewhere in GA, then back to Nashville.

If you keep it simple, do the regular maintenance stuff, you should be fine. However, I do like to keep a fire extinguisher and basic tools in car.

Good luck and let us know how it turns out.